I'm moving and I have two 8 month old kittens (sisters)?

and they're really attached to each other but one is mine and the other's is my stepmom's and i'm moving but i can only take mine!!! there's another cat where i'm moving but i'm wondering if she'll be able to handle being w/o her sis? my stepmom wont let me take the other kitten and i HAVE to bring my baby, i love her!!!