I messed up during registration when it asked for "member number" and I wasn't sure what that meant (would have been much clearer to ask for "frequent flyer number" or something like that), and now I'm trying to get it fixed. They definitely don't want people hopping around between programs, but my main use for iDine conflicts with that somewhat because I want to use it to top off "orphan" miles. So it indeed looks like it'll require a different card for each program.