When you find the females it’s important to keep them in separate rooms for at least 30 days before introducing to your males. If you bring birds into your home, that may be carrying a disease or virus, it could be passed on to your males.
After the quarantine period is completed, it’s important to get a cage that’s twice the size of the cage the males are in now. It’s important to make sure there are three feeding stations as well as three separate places in the cage to hang their nests. Make sure they are as far apart as possible. Once birds pair up, they can become very territorial and gang up and bully the other pair. You may actually see a version of this while they are deciding who they want to pair up with.
Keeping all these things in mind, you may still need to place them in separate cages if and when they start nesting.
As for your other question, yes Zebra finches are known to be very good parents. The male and female work as a team in caring for the eggs and rearing the babies. In case you’re interested, many serious finch breeders will have a few stable pair of Zebra finches available to raise other bird’s babies such as Gouldian’s which are not known for being good parents.
So, if you do everything we discussed, you should have a very positive experience with them if you decide to let them breed.
Good Luck,
Debbie