Do they make 'cute' crates?
I have mostly had multiples of all sizes and never had a problem. I just got my new baby last month and at first Chloe Primrose was like...what is that thing in My house!!! But within a week they were real sisters and without any fights or real nasty behavior. I keep a close watch as there is a difference in size but I am sure you all will do well.
I bet you just can't wait. Congratulations and have a happy!