First, I already have ideas for all of the Jinchuuriki so only a few, if any, of those apps will be NPCs, as there has to be some in the Jubi Corps and in other villages, etc.
And as I mentioned to Double, I'm going to give time after selection to tie in backgrounds as desired before we start. After all, by and large you will have known each other or at least of each other.
Another precedent would be the Kyuubi itself, as only half of its chakra was sealed into Naruto, though I don't think you could actually make multiple Jichuuriki since there's a difference between having a demon sealed in you and having demonic chakra sealed in you. Only one has a will and a mind.
Edit: Hah, ninja'd!