Introducing two new rats to my current rats

Question
I just adopted two adult albino females ( Nillie and Waffer) from a pet store because they had been there awhile and I didn't think anyone else would take them. They came with their own cage setup and everything. I already owned two rats named Pino and Sennex and I've had them since they were babies, they're really attached to me as I am to them and they're about the same age as Nillie and Waffer.
I have their cages close to each other so they can sniff but not touch, they've already met on my bed and Sennex and Nillie (who's a bit of a biter) got into a fight so I seperated them and they haven't "hung out" since. Nillie and Waffer are pretty timmid and don't like being handled so I'm not sure if they'll ever be able to be cage mates with my two outgoing sweet rats. However, I'm not going to just give up on the new babies!
Any advice on how I can try to get them to be more social and introduce them to the bigger cage with Sennex and Pino?

Answer
Hi Margaret,
God bless you for rescuing these poor girls! No doubt they are poorly socialized, as many pet shop rat are unfortunately, but there is an article called Trust Training on my website at www.ratfanclub.org on the Rat Info page that will tell you how to gain their trust. You'll also find an article about introducing new rats. Nillie and Waffer might be more willing to trust you if they can bond with Sennex and Pino and then follow their example.

I invite you to join a non-profit I run that has as our main goal, improving the way rats and mice are sold in pet shops. The website is at www.petrats.org.
Deb