diff --git a/action.yml b/action.yml
index de5c6116..a5ba9633 100644
--- a/action.yml
+++ b/action.yml
@@ -190,6 +190,13 @@ inputs:
     default: |
       $filename
 
+      Existing comments on the patch, though some of them may be outdated. 
+      Please use them as additional context.
+      ```
+      $comment_chain
+      ```
+
+      Diff for review:
       ```diff
       $patch
       ```
@@ -259,7 +266,8 @@ inputs:
       ```
 
       Please reply directly to the new comment in the conversation 
-      chain without extra prose as that reply will be posted as-is.
+      chain (instead of suggesting a reply) and your reply will be 
+      posted as-is.
 
       In your reply, please make sure to begin the reply by
       tagging the user with "@user".
diff --git a/dist/index.js b/dist/index.js
index e72d5a03..7faa9a45 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -27134,55 +27134,85 @@ class Commenter {
             _actions_core__WEBPACK_IMPORTED_MODULE_0__.warning(`Failed to get PR: ${e}, skipping adding release notes to description.`);
         }
     }
-    async review_comment(pull_number, commit_id, path, line, message, tag = COMMENT_TAG) {
+    async review_comment(pull_number, commit_id, path, line, message) {
         message = `${COMMENT_GREETING}
 
 ${message}
 
-${tag}`;
+${COMMENT_TAG}`;
         // replace comment made by this action
         try {
-            const comments = await this.list_review_comments(pull_number);
+            let found = false;
+            const comments = await this.get_comments_at_line(pull_number, path, line);
             for (const comment of comments) {
-                if (comment.path === path && comment.position === line) {
-                    // look for tag
-                    if (comment.body && comment.body.includes(tag)) {
-                        await octokit.pulls.updateReviewComment({
-                            owner: repo.owner,
-                            repo: repo.repo,
-                            comment_id: comment.id,
-                            body: message
-                        });
-                        return;
-                    }
+                if (comment.body.includes(COMMENT_TAG)) {
+                    await octokit.pulls.updateReviewComment({
+                        owner: repo.owner,
+                        repo: repo.repo,
+                        comment_id: comment.id,
+                        body: message
+                    });
+                    found = true;
+                    break;
                 }
             }
-            await octokit.pulls.createReviewComment({
-                owner: repo.owner,
-                repo: repo.repo,
-                pull_number,
-                body: message,
-                commit_id,
-                path,
-                line
-            });
+            if (!found) {
+                await octokit.pulls.createReviewComment({
+                    owner: repo.owner,
+                    repo: repo.repo,
+                    pull_number,
+                    body: message,
+                    commit_id,
+                    path,
+                    line
+                });
+            }
         }
         catch (e) {
             _actions_core__WEBPACK_IMPORTED_MODULE_0__.warning(`Failed to post review comment: ${e}`);
         }
     }
-    async getConversationChain(pull_number, comment) {
+    async get_comments_at_line(pull_number, path, line) {
+        const comments = await this.list_review_comments(pull_number);
+        return comments.filter((comment) => comment.path === path && comment.line === line && comment.body !== '');
+    }
+    async get_conversation_chains_at_line(pull_number, path, line, tag = '') {
+        const existing_comments = await this.get_comments_at_line(pull_number, path, line);
+        // find all top most comments
+        const top_level_comments = [];
+        for (const comment of existing_comments) {
+            if (!comment.in_reply_to_id) {
+                top_level_comments.push(comment);
+            }
+        }
+        let all_chains = '';
+        let chain_num = 0;
+        for (const top_level_comment of top_level_comments) {
+            // get conversation chain
+            const chain = await this.compose_conversation_chain(existing_comments, top_level_comment);
+            if (chain && chain.includes(tag)) {
+                chain_num += 1;
+                all_chains += `Conversation Chain ${chain_num}:
+${chain}
+---
+`;
+            }
+        }
+        return all_chains;
+    }
+    async compose_conversation_chain(reviewComments, topLevelComment) {
+        const conversationChain = reviewComments
+            .filter((cmt) => cmt.in_reply_to_id === topLevelComment.id)
+            .map((cmt) => `${cmt.user.login}: ${cmt.body}`);
+        conversationChain.unshift(`${topLevelComment.user.login}: ${topLevelComment.body}`);
+        return conversationChain.join('\n---\n');
+    }
+    async get_conversation_chain(pull_number, comment) {
         try {
-            const reviewComments = await this.list_review_comments(pull_number);
-            const topLevelComment = await this.getTopLevelComment(reviewComments, comment);
-            const conversationChain = reviewComments
-                .filter((cmt) => cmt.in_reply_to_id === topLevelComment.id)
-                .map((cmt) => `${cmt.user.login}: ${cmt.body}`);
-            conversationChain.unshift(`${topLevelComment.user.login}: ${topLevelComment.body}`);
-            return {
-                chain: conversationChain.join('\n---\n'),
-                topLevelComment
-            };
+            const review_comments = await this.list_review_comments(pull_number);
+            const top_level_comment = await this.get_top_level_comment(review_comments, comment);
+            const chain = await this.compose_conversation_chain(review_comments, top_level_comment);
+            return { chain, topLevelComment: top_level_comment };
         }
         catch (e) {
             _actions_core__WEBPACK_IMPORTED_MODULE_0__.warning(`Failed to get conversation chain: ${e}`);
@@ -27192,40 +27222,42 @@ ${tag}`;
             };
         }
     }
-    async getTopLevelComment(reviewComments, comment) {
-        let topLevelComment = comment;
-        while (topLevelComment.in_reply_to_id) {
-            const parentComment = reviewComments.find((cmt) => cmt.id === topLevelComment.in_reply_to_id);
-            if (parentComment) {
-                topLevelComment = parentComment;
+    async get_top_level_comment(reviewComments, comment) {
+        let top_level_comment = comment;
+        while (top_level_comment.in_reply_to_id) {
+            const parent_comment = reviewComments.find((cmt) => cmt.id === top_level_comment.in_reply_to_id);
+            if (parent_comment) {
+                top_level_comment = parent_comment;
             }
             else {
                 break;
             }
         }
-        return topLevelComment;
+        return top_level_comment;
     }
-    async list_review_comments(target, page = 1) {
-        const comments = [];
+    async list_review_comments(target) {
+        const all_comments = [];
+        let page = 1;
         try {
-            let data;
-            do {
-                ;
-                ({ data } = await octokit.pulls.listReviewComments({
+            for (;;) {
+                const { data: comments } = await octokit.pulls.listReviewComments({
                     owner: repo.owner,
                     repo: repo.repo,
                     pull_number: target,
                     page,
                     per_page: 100
-                }));
-                comments.push(...data);
+                });
+                all_comments.push(...comments);
                 page++;
-            } while (data.length >= 100);
-            return comments;
+                if (!comments || comments.length < 100) {
+                    break;
+                }
+            }
+            return all_comments;
         }
         catch (e) {
             console.warn(`Failed to list review comments: ${e}`);
-            return comments;
+            return all_comments;
         }
     }
     async post_comment(message, tag, mode) {
@@ -27350,27 +27382,29 @@ ${tag}`;
             return null;
         }
     }
-    async list_comments(target, page = 1) {
-        const comments = [];
+    async list_comments(target) {
+        const all_comments = [];
+        let page = 1;
         try {
-            let data;
-            do {
-                ;
-                ({ data } = await octokit.issues.listComments({
+            for (;;) {
+                const { data: comments } = await octokit.issues.listComments({
                     owner: repo.owner,
                     repo: repo.repo,
                     issue_number: target,
                     page,
                     per_page: 100
-                }));
-                comments.push(...data);
+                });
+                all_comments.push(...comments);
                 page++;
-            } while (data.length >= 100);
-            return comments;
+                if (!comments || comments.length < 100) {
+                    break;
+                }
+            }
+            return all_comments;
         }
         catch (e) {
             console.warn(`Failed to list comments: ${e}`);
-            return comments;
+            return all_comments;
         }
     }
 }
@@ -29022,7 +29056,7 @@ class Inputs {
     diff;
     comment_chain;
     comment;
-    constructor(system_message = '', title = 'no title provided', description = 'no description provided', summary = 'no summary so far', filename = '', file_content = '', file_diff = '', patch = '', diff = '', comment_chain = '', comment = '') {
+    constructor(system_message = '', title = 'no title provided', description = 'no description provided', summary = 'no summary so far', filename = 'unknown', file_content = 'file contents cannot be provided', file_diff = 'file diff cannot be provided', patch = 'patch cannot be provided', diff = 'no diff', comment_chain = 'no other comments on this patch', comment = 'no comment provided') {
         this.system_message = system_message;
         this.title = title;
         this.description = description;
@@ -29204,7 +29238,7 @@ const handleReviewComment = async (bot, prompts) => {
         const diff = comment.diff_hunk;
         inputs.comment = `${comment.user.login}: ${comment.body}`;
         inputs.diff = diff;
-        const { chain: comment_chain, topLevelComment } = await commenter.getConversationChain(pull_number, comment);
+        const { chain: comment_chain, topLevelComment } = await commenter.get_conversation_chain(pull_number, comment);
         inputs.comment_chain = comment_chain;
         // check whether this chain contains replies from the bot
         if (comment_chain.includes(_commenter_js__WEBPACK_IMPORTED_MODULE_2__/* .COMMENT_TAG */ .Rs) ||
@@ -29530,6 +29564,14 @@ Tips:
             for (const [line, patch] of patches) {
                 _actions_core__WEBPACK_IMPORTED_MODULE_0__.info(`Reviewing ${filename}:${line} with openai ...`);
                 inputs.patch = patch;
+                // get existing comments on the line
+                const all_chains = await commenter.get_conversation_chains_at_line(context.payload.pull_request.number, filename, line, _commenter_js__WEBPACK_IMPORTED_MODULE_2__/* .COMMENT_REPLY_TAG */ .aD);
+                if (all_chains.length > 0) {
+                    inputs.comment_chain = all_chains;
+                }
+                else {
+                    inputs.comment_chain = 'no previous comments';
+                }
                 const [response, patch_ids] = await bot.chat(prompts.render_review_patch(inputs), next_review_ids);
                 if (!response) {
                     _actions_core__WEBPACK_IMPORTED_MODULE_0__.info('review: nothing obtained from openai');
diff --git a/src/commenter.ts b/src/commenter.ts
index 5ec7053c..8c4a8051 100644
--- a/src/commenter.ts
+++ b/src/commenter.ts
@@ -100,66 +100,119 @@ export class Commenter {
     commit_id: string,
     path: string,
     line: number,
-    message: string,
-    tag: string = COMMENT_TAG
+    message: string
   ) {
     message = `${COMMENT_GREETING}
 
 ${message}
 
-${tag}`
+${COMMENT_TAG}`
     // replace comment made by this action
     try {
-      const comments = await this.list_review_comments(pull_number)
+      let found = false
+      const comments = await this.get_comments_at_line(pull_number, path, line)
       for (const comment of comments) {
-        if (comment.path === path && comment.position === line) {
-          // look for tag
-          if (comment.body && comment.body.includes(tag)) {
-            await octokit.pulls.updateReviewComment({
-              owner: repo.owner,
-              repo: repo.repo,
-              comment_id: comment.id,
-              body: message
-            })
-            return
-          }
+        if (comment.body.includes(COMMENT_TAG)) {
+          await octokit.pulls.updateReviewComment({
+            owner: repo.owner,
+            repo: repo.repo,
+            comment_id: comment.id,
+            body: message
+          })
+          found = true
+          break
         }
       }
 
-      await octokit.pulls.createReviewComment({
-        owner: repo.owner,
-        repo: repo.repo,
-        pull_number,
-        body: message,
-        commit_id,
-        path,
-        line
-      })
+      if (!found) {
+        await octokit.pulls.createReviewComment({
+          owner: repo.owner,
+          repo: repo.repo,
+          pull_number,
+          body: message,
+          commit_id,
+          path,
+          line
+        })
+      }
     } catch (e: any) {
       core.warning(`Failed to post review comment: ${e}`)
     }
   }
 
-  async getConversationChain(pull_number: number, comment: any) {
-    try {
-      const reviewComments = await this.list_review_comments(pull_number)
-      const topLevelComment = await this.getTopLevelComment(
-        reviewComments,
-        comment
-      )
+  async get_comments_at_line(pull_number: number, path: string, line: number) {
+    const comments = await this.list_review_comments(pull_number)
+    return comments.filter(
+      (comment: any) =>
+        comment.path === path && comment.line === line && comment.body !== ''
+    )
+  }
 
-      const conversationChain = reviewComments
-        .filter((cmt: any) => cmt.in_reply_to_id === topLevelComment.id)
-        .map((cmt: any) => `${cmt.user.login}: ${cmt.body}`)
+  async get_conversation_chains_at_line(
+    pull_number: number,
+    path: string,
+    line: number,
+    tag: string = ''
+  ) {
+    const existing_comments = await this.get_comments_at_line(
+      pull_number,
+      path,
+      line
+    )
+    // find all top most comments
+    const top_level_comments = []
+    for (const comment of existing_comments) {
+      if (!comment.in_reply_to_id) {
+        top_level_comments.push(comment)
+      }
+    }
 
-      conversationChain.unshift(
-        `${topLevelComment.user.login}: ${topLevelComment.body}`
+    let all_chains = ''
+    let chain_num = 0
+    for (const top_level_comment of top_level_comments) {
+      // get conversation chain
+      const chain = await this.compose_conversation_chain(
+        existing_comments,
+        top_level_comment
       )
-
-      return {
-        chain: conversationChain.join('\n---\n'),
-        topLevelComment
+      if (chain && chain.includes(tag)) {
+        chain_num += 1
+        all_chains += `Conversation Chain ${chain_num}:
+${chain}
+---
+`
       }
+    }
+    return all_chains
+  }
+
+  async compose_conversation_chain(
+    reviewComments: any[],
+    topLevelComment: any
+  ) {
+    const conversationChain = reviewComments
+      .filter((cmt: any) => cmt.in_reply_to_id === topLevelComment.id)
+      .map((cmt: any) => `${cmt.user.login}: ${cmt.body}`)
+
+    conversationChain.unshift(
+      `${topLevelComment.user.login}: ${topLevelComment.body}`
+    )
+
+    return conversationChain.join('\n---\n')
+  }
+
+  async get_conversation_chain(pull_number: number, comment: any) {
+    try {
+      const review_comments = await this.list_review_comments(pull_number)
+      const top_level_comment = await this.get_top_level_comment(
+        review_comments,
+        comment
+      )
+      const chain = await this.compose_conversation_chain(
+        review_comments,
+        top_level_comment
+      )
+      return {chain, topLevelComment: top_level_comment}
     } catch (e: any) {
       core.warning(`Failed to get conversation chain: ${e}`)
       return {
@@ -169,44 +222,47 @@ ${tag}`
     }
   }
 
-  async getTopLevelComment(reviewComments: any[], comment: any) {
-    let topLevelComment = comment
+  async get_top_level_comment(reviewComments: any[], comment: any) {
+    let top_level_comment = comment
 
-    while (topLevelComment.in_reply_to_id) {
-      const parentComment = reviewComments.find(
-        (cmt: any) => cmt.id === topLevelComment.in_reply_to_id
+    while (top_level_comment.in_reply_to_id) {
+      const parent_comment = reviewComments.find(
+        (cmt: any) => cmt.id === top_level_comment.in_reply_to_id
       )
 
-      if (parentComment) {
-        topLevelComment = parentComment
+      if (parent_comment) {
+        top_level_comment = parent_comment
       } else {
         break
       }
     }
 
-    return topLevelComment
+    return top_level_comment
   }
 
-  async list_review_comments(target: number, page: number = 1) {
-    const comments: any[] = []
+  async list_review_comments(target: number) {
+    const all_comments: any[] = []
+    let page = 1
     try {
-      let data
-      do {
-        ;({data} = await octokit.pulls.listReviewComments({
+      for (;;) {
+        const {data: comments} = await octokit.pulls.listReviewComments({
           owner: repo.owner,
           repo: repo.repo,
           pull_number: target,
           page,
           per_page: 100
-        }))
-        comments.push(...data)
+        })
+        all_comments.push(...comments)
         page++
-      } while (data.length >= 100)
+        if (!comments || comments.length < 100) {
+          break
+        }
+      }
 
-      return comments
+      return all_comments
     } catch (e: any) {
       console.warn(`Failed to list review comments: ${e}`)
-      return comments
+      return all_comments
     }
   }
 
@@ -330,27 +386,29 @@ ${tag}`
     }
   }
 
-  async list_comments(target: number, page: number = 1) {
-    const comments: any[] = []
+  async list_comments(target: number) {
+    const all_comments: any[] = []
+    let page = 1
     try {
-      let data
-      do {
-        ;({data} = await octokit.issues.listComments({
+      for (;;) {
+        const {data: comments} = await octokit.issues.listComments({
           owner: repo.owner,
           repo: repo.repo,
           issue_number: target,
           page,
           per_page: 100
-        }))
-
-        comments.push(...data)
+        })
+        all_comments.push(...comments)
         page++
-      } while (data.length >= 100)
+        if (!comments || comments.length < 100) {
+          break
+        }
+      }
 
-      return comments
+      return all_comments
     } catch (e: any) {
       console.warn(`Failed to list comments: ${e}`)
-      return comments
+      return all_comments
     }
   }
 }
diff --git a/src/options.ts b/src/options.ts
index 1ad38578..972e3ed3 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -113,13 +113,13 @@ export class Inputs {
     title = 'no title provided',
     description = 'no description provided',
     summary = 'no summary so far',
-    filename = '',
-    file_content = '',
-    file_diff = '',
-    patch = '',
-    diff = '',
-    comment_chain = '',
-    comment = ''
+    filename = 'unknown',
+    file_content = 'file contents cannot be provided',
+    file_diff = 'file diff cannot be provided',
+    patch = 'patch cannot be provided',
+    diff = 'no diff',
+    comment_chain = 'no other comments on this patch',
+    comment = 'no comment provided'
   ) {
     this.system_message = system_message
     this.title = title
diff --git a/src/review-comment.ts b/src/review-comment.ts
index 4937e8d9..e93d5286 100644
--- a/src/review-comment.ts
+++ b/src/review-comment.ts
@@ -70,7 +70,7 @@ export const handleReviewComment = async (bot: Bot, prompts: Prompts) => {
     inputs.diff = diff
 
     const {chain: comment_chain, topLevelComment} =
-      await commenter.getConversationChain(pull_number, comment)
+      await commenter.get_conversation_chain(pull_number, comment)
     inputs.comment_chain = comment_chain
 
     // check whether this chain contains replies from the bot
diff --git a/src/review.ts b/src/review.ts
index 0b9052fb..a15082e9 100644
--- a/src/review.ts
+++ b/src/review.ts
@@ -2,7 +2,7 @@ import * as core from '@actions/core'
 import * as github from '@actions/github'
 import {Octokit} from '@octokit/action'
 import {Bot} from './bot.js'
-import {Commenter, SUMMARIZE_TAG} from './commenter.js'
+import {Commenter, COMMENT_REPLY_TAG, SUMMARIZE_TAG} from './commenter.js'
 import {Inputs, Options, Prompts} from './options.js'
 import * as tokenizer from './tokenizer.js'
 
@@ -263,6 +263,21 @@ Tips:
       for (const [line, patch] of patches) {
         core.info(`Reviewing ${filename}:${line} with openai ...`)
         inputs.patch = patch
+
+        // get existing comments on the line
+        const all_chains = await commenter.get_conversation_chains_at_line(
+          context.payload.pull_request.number,
+          filename,
+          line,
+          COMMENT_REPLY_TAG
+        )
+
+        if (all_chains.length > 0) {
+          inputs.comment_chain = all_chains
+        } else {
+          inputs.comment_chain = 'no previous comments'
+        }
+
         const [response, patch_ids] = await bot.chat(
           prompts.render_review_patch(inputs),
           next_review_ids