I have a pair of zebra finches they are in a 42 inch wide, 22 inch deep and 37 inch tall cage. My local pet store is saying I could put 8 finches in there (4 pairs). I want to make sure that is appropriate and he is not just trying to get me to buy more. How many finches could that cage house with the finches still being happy? I would like to house 2 pairs in that cage together but have been made aware that it may not work out. Is there any tricks to help? I have them next to each other so they can "get used" to one another. I appreciate your time!