I'm new to PetForums, so firstly HI! I've been thinking of finding a good pet forum for a while so I'm glad I've found one. Now, I'm a future cat owner, meaning I currently do not own any pets. I plan on getting two cats as soon as I move into my own place. I know Birman cats are larger sized, whereas Russian Blues are medium sized cats. Would this be an issue or can they live together happily?