Hi! I'll DM you to get more details. We'll get those kitten profiles on your phone asap. And, yes, Dr. Sheila is correct, the surveys are on behalf of the litter, so that will function as usual with just the one littermate.
It sounds like you're using the app through a shelter, so all the kittens should be there. In a few months you'll be able to add kittens yourself, but right now the shelter has to do it for you. The app should be able to help you, however, with just one kitten... you get one survey for all the kittens in a litter. Does that make sense?