Im not really sure about the size, but will you keep them together??? I am going to get a nother bp and im going to keep both of mine together so some people dont like it but i dont see a problem with it as long as there isnt a big size difference. QUARANTINE is necessary. Im going to be having my second one quarantined for about 8 weeks so anywhere from 2 to 3 months would be good. Good luck, by the way what kind do you have and what kind are you getting, i wouldnt get a bp from a petstore unless you know where its coming from i would get one from a breeder, where are you located, most of the time you can find a local breeder that would sell you a normal for $50 if thats the kind your getting.