No worries - every exchange is different. Having a separate fandom for crossovers is what most of them do nowadays, but it's not a hard and fast rule by any means.

I've added your crossover pairings in now - don't be alarmed if you go back to your nomination page and see that they're rejected - I put them in a different way. It just saves me an extra step, is all.

Feel free to get in touch if you change your mind and want to use more of your nomination slots!