Currently selecting an old replay will give us "obsolete replay" and the option to rename or delete. How about a button to move all obsolete replays into a folder that has the name of the version the replay needs to run. For example putting an obsolete replay into mpr/s2 Q/replayname.mpr. This way if we want to view an old replay we know what version we need to find.

Also a delete all obsolete replays button would be nice. I have about 50 obsolete MPR replays and probably about 200 obsolete spr replays. I think it would be nice to be able to manage these replays from LFS.

Not a bad suggestion, but You could just find the last obsolete replay in the Replay screen, remember it's name, than quit to windows, go to the data/mpr folder, arrange files by date of last modification, and then move the files older than the replay U remembered :P
I for example have 2 versions of LFS installed, so I can view some older replays, if I want to