Mixing Gerbils

I have a question... My two gerbils, Storm and Dusty, aren't very alike and I'd like to adopt several more females since I have the room and will spend the money for it since Gerbils hit me in a soft spot. However, I adopted the two I have now together so they have known each other and could even be related, I'm not 100% sure.

Anyways, if I do adopt more, how should I go about "greeting" the new ones to Storm and Dusty? I really don't want to do seperate cages because I like them to be interconnected so I was hoping there would be some way to properly show them to my gerbils and have them all get along. Is that possible? And if it is, how do I go about it so that Storm and Dusty don't feel violated of their space? If there is a proper way to do it, will the procedure work with the newer and older gerbils if more come in? Thanks so much!

KyDust