Thank you! H and I will call her Katherine and probably something random. (X's nn is monkey) Our preference for a nn is Kate if family wants to shorten her first name.
Great name! And the spelling is spot on. I've heard 'Kat' is a good nn. :Y: FWIW, I was 'Katie' until like 10, then I went by my full name until 18. DH started calling me Kat and now everyone does.