Great informative post Sue !
Im in the same situation - Poppy is only registered with TICA so im in the process of registering with GCCF so I can duel register the kitten im hoping to keep. The certified ped came really quickly from TICA which was great.
If you dont have time etc to register your prefix with GCCF you can still reg the kittens but you will have to use one of their preset prefixes - you can then add your prefix in the ped name - I think this is what I will be doing with my keeper kitty so she will be eligeable for showing with both bodies - ps I cant take the credit for this advice though as was from a friend