Sisters Living Together

[VanessaS]

Hi everyone!
I have recently, one day ago, saved two sweet Syrian girls from a bad end and I have a question.
These two sisters were born at the beginning of 2012 and have happily lived together their whole lives. They are always sleeping and cuddling together and I have yet to see any signs of aggression. I have checked both of them over for signs of wounds or fighting and I don't see anything to indicate fights. The cage that they have been living in is far too small, so I bought them a more appropriate cage today and they seem very happy in it.
What are the chances that this will continue? Has anyone ever had two females live out their lives together?
I have had a number of Syrian's in the past and I know that they are solitary little creatures and can do serious damage if housed together. I have had up to three at one time but they were housed separately and were never allowed to come in contact with each other. I know that it is a big no-no to keep them together but the girls are getting along so well and I don't want to separate them unnecessarily.
What are the chances that I won't have to?