How can I edit two posts at the same time?

[DivinoZarathos]

I'm building a vB modification that allows moderators to duplicate a post and insert it in another existing thread only once. I added a column to the post sql table that keeps track of the "link" between the two posts.
I can already delete both posts if one of them is deleted, but now I would like to create a specular post editing system so that if one of the two posts is edited, the other reflects the same changes.
Let's say I have a post with ID=10. It is duplicated by a mod and inserted into another thread: the duplicated post has ID=11. Now in my database post ID=10 will have LINKID=11 and post ID=11 will have LINKID=10.
How can I hook into editpost.php so that if I edit post ID=10, post ID=11 also get edited and vice-versa?

Many thanks.