I don't think it is that easy....
someone correct me if I'm wrong here.....but I believe there is only ONE custom team save file allowed per PS3 user profile....
so lets say I made the 9ers....and you made the Saints.....now if I copy your Saints file (which would be call Custom Team save) to my profile on my PS3....it will tell me if I want to over write my "Custom Team save" which has my 9ers....
same thing if one person made all the NFL teams.....and another person made all the rosters.....they can't combine them....one of those files will have to be over writen (deleted)
that is why I say we should have one person do all the rosters....and then when he is finished, he can give that Custom Team Save to another person who is good at creating logos and uniforms.....and then that person can edit every uniform for each team, which has the correct rosters already.....and when he is finished....we can all download the complete teams and roster file...
also while we are waiting for our talented graphic artist finish up the teams....we can still download a copy of the rosters file...and just play with NFL rosters with genaric uniform teams....until our artist is finished.