diff --git a/app/activitypub/util.py b/app/activitypub/util.py
index 428c7901..e7a37d2a 100644
--- a/app/activitypub/util.py
+++ b/app/activitypub/util.py
@@ -1397,6 +1397,20 @@ def create_post(activity_log: ActivityPubLog, community: Community, request_json
         if post.image_id:
             make_image_sizes(post.image_id, 150, 512, 'posts')  # the 512 sized image is for masonry view
 
+        if post.url:
+            other_posts = Post.query.filter(Post.id != post.id, Post.url == post.url,
+                                    Post.posted_at > post.posted_at - timedelta(days=6)).all()
+            for op in other_posts:
+                if op.cross_posts is None:
+                    op.cross_posts = [post.id]
+                else:
+                    op.cross_posts.append(post.id)
+                if post.cross_posts is None:
+                    post.cross_posts = [op.id]
+                else:
+                    post.cross_posts.append(op.id)
+            db.session.commit()
+
         notify_about_post(post)
 
         if user.reputation > 100:
@@ -1503,6 +1517,27 @@ def update_post_from_activity(post: Post, request_json: dict):
             post.domain = domain
         else:
             post.url = old_url              # don't change if url changed from non-banned domain to banned domain
+
+        new_cross_posts = Post.query.filter(Post.id != post.id, Post.url == post.url,
+                                    Post.posted_at > utcnow() - timedelta(days=6)).all()
+        for ncp in new_cross_posts:
+            if ncp.cross_posts is None:
+                ncp.cross_posts = [post.id]
+            else:
+                ncp.cross_posts.append(post.id)
+            if post.cross_posts is None:
+                post.cross_posts = [ncp.id]
+            else:
+                post.cross_posts.append(ncp.id)
+
+    if post.url != old_url:
+        if post.cross_posts is not None:
+            old_cross_posts = Post.query.filter(Post.id.in_(post.cross_posts)).all()
+            post.cross_posts.clear()
+            for ocp in old_cross_posts:
+                if ocp.cross_posts is not None:
+                    ocp.cross_posts.remove(post.id)
+
     if post is not None:
         if 'image' in request_json['object'] and post.image is None:
             image = File(source_url=request_json['object']['image']['url'])
diff --git a/app/community/routes.py b/app/community/routes.py
index 87c44739..07aba09a 100644
--- a/app/community/routes.py
+++ b/app/community/routes.py
@@ -470,6 +470,20 @@ def add_post(actor):
         if post.image_id and post.image.file_path is None:
             make_image_sizes(post.image_id, 150, 512, 'posts')  # the 512 sized image is for masonry view
 
+        if post.url:
+            other_posts = Post.query.filter(Post.id != post.id, Post.url == post.url,
+                                    Post.posted_at > post.posted_at - timedelta(days=6)).all()
+            for op in other_posts:
+                if op.cross_posts is None:
+                    op.cross_posts = [post.id]
+                else:
+                    op.cross_posts.append(post.id)
+                if post.cross_posts is None:
+                    post.cross_posts = [op.id]
+                else:
+                    post.cross_posts.append(op.id)
+            db.session.commit()
+
         notify_about_post(post)
 
         if not community.local_only:
diff --git a/app/post/routes.py b/app/post/routes.py
index 57082fcf..6647d271 100644
--- a/app/post/routes.py
+++ b/app/post/routes.py
@@ -1,5 +1,5 @@
 from collections import namedtuple
-from datetime import datetime
+from datetime import datetime, timedelta
 from random import randint
 
 from flask import redirect, url_for, flash, current_app, abort, request, g, make_response
@@ -683,12 +683,36 @@ def post_edit(post_id: int):
             form.nsfw.render_kw = {'disabled': True}
 
         #form.communities.choices = [(c.id, c.display_name()) for c in current_user.communities()]
+        old_url = post.url
 
         if form.validate_on_submit():
             save_post(form, post)
             post.community.last_active = utcnow()
             post.edited_at = utcnow()
             db.session.commit()
+
+            if post.url != old_url:
+                if post.cross_posts is not None:
+                    old_cross_posts = Post.query.filter(Post.id.in_(post.cross_posts)).all()
+                    post.cross_posts.clear()
+                    for ocp in old_cross_posts:
+                        if ocp.cross_posts is not None:
+                            ocp.cross_posts.remove(post.id)
+
+                new_cross_posts = Post.query.filter(Post.id != post.id, Post.url == post.url,
+                                                Post.posted_at > post.edited_at - timedelta(days=6)).all()
+                for ncp in new_cross_posts:
+                    if ncp.cross_posts is None:
+                        ncp.cross_posts = [post.id]
+                    else:
+                        ncp.cross_posts.append(post.id)
+                    if post.cross_posts is None:
+                        post.cross_posts = [ncp.id]
+                    else:
+                        post.cross_posts.append(ncp.id)
+
+                db.session.commit()
+
             post.flush_cache()
             flash(_('Your changes have been saved.'), 'success')
             # federate edit