If I were to buy a female, would she and one of the males have to become permanent cage mates? Or could I mate them, and then put the male back with his buddy?
Now that's a mouth full of a question and Jo Ann is so much better with all the details than I am.
But for starters it's quite possible that if you add a female to the same room and she goes in heat, that the boys could fight to the death to get at her.
Are you willing to take that chance?
As it stands your males have never gotten the scent of a female in heat and don't know what they are missing. Once they do they become men in chin land, and will never forget that feeling
So the short answer is NO.
Your going to hear all kinds of reasons why not, and MAYBE one or two whom have had something like that work, but I've been breeding for 12 years and I wouldn't even bother trying.
There are routs you could take to breed them like putting her with one of them for life. You could keep introducing her back and forth with both. Or if you want to keep these two boys together, buy a new breeding pair.
You have to decide if you want breeding pairs, runs or colonies, and if you wish to sell kits or just breed a few more pets for yourself?
There's so much to think about and learn, I'm so glad your doing your homework first.