Is it possible you might have seen the term "colony" breeding and misunderstood what it meant? Colony breeding is when you put one male with multiple females in a large cage. You don't put multiple males with multiple females in the same cage.
I'm also very worried about your comment that you put them together at a young age. No female should go into breeding before she's 8 months of age, and even then it's usually black velvets that get started early because they can be stubborn about breeding. Most hobbyists hold their female chins out of breeding until they are 8 months to at least a year. Putting them in too young can cause several issues; first it can be dangerous for mom to give birth because the mom may simply not have enough room for the kits to pass through at birth. There is also the issue of what kind of drain it puts on mom. Mom needs to be in peak physical condition to have kits. If she's still a baby herself, then you are taking vital nutrients away from her that would allow her to grow to her full potential, and in turn, you could end up with a mom who won't produce milk because her body just isn't fully matured. That means you, the breader, get to hand feed those kits every 2 hours, around the clock, 24 hours a day, 7 days a week until they are at least 2 weeks old, possibly 3. After that, you still have to hand feed them every 3-4 hours until they are ready to wean at 6-8 weeks.
I understand that you want cute, fuzzy babies, but there is a right way and an incredibly wrong way to go about producing them and the way you are doing it right now is not only wrong, it's very, very dangerous for all the animals involved.