ill try it but i think a timestamp is also required.
also i found a window of oppurtunity where the saves arent checked or resynced. during this window you can edit the save or replace them with another save. then load and resave and itll sync your new save to your account.
edit
tried your save and replaced the signature in the xml with the one you posted and it gets deleted.
i guess i was wrong about the timestamp. if i change or delete the timestamp of a save it will stay
on that first xml i posted. there is only one save to save00 the rest of the signatures are for empty no save places. this signature is the same for all users with blank spots.
cc3eee5cb5b1c7a08a776ffdfb6618c9
i tried copying a save and signature from someone else and it gets deleted
this is where my new saves go to.
C:\Users\LUTZ\Documents\Square Enix\FINAL FANTASY VII\user_260359
here are my new save files and metadata along with another users saves and metadata
https://rapidshare.com/files/2415538029/savefiles.zip