Seriously. I love how many people are holding conversations over fragments when the PM system is actually much better suited for that. Well, unless you want to randomly have other people look at your conversation, which I can understand to an extent. But… it’s really not designed for that!
Might as well just implement wall posts, really, and make fragments that are actually fragments post to the user’s own wall.
To add onto the suggestion, though, as-is, PM ping notices could quote the fragment and then give the reply link, as well.