Sometimes I make a post and later decide to add to it. The simple solution is to edit the post. However editing is less convenient than creating a new post when:

1. Quick reply is enabled.
2. I want to quote some other post.

Ideally, when making a new post, if I have the last post in the topic being replied to, I should see a checkbox saying "append the contents of this post to my last post in this topic" that I could check to avoid creating multiple consecutive posts.

To avoid adding options to quick reply, perhaps this operation can be unconditional when quick reply is used.