the current iteration of quoting only allows you to quote entire posts/replies. If that post or reply has multiple points of discussion, there's no way to specify which part you're addressing
(I promise I tried searching for this before posting)
Apparently there is a way to do this manually but 1) it doesn't indicate who said what and 2) you can make things up
It's a blunt tool, to be sure. Though I don't know if it could be improved.