Yep I do that too lol !Not only do I not take away the chicks from the moms, but I try to time incubator hatches with the hen's hatches, so I can foist off the incubator chicks on the new moms and not have to raise them myself.
Right now, I have 7 moms raising chicks, poults, and keets. They have traded chicks around all over, so some have groups ranging in age from 1 week to 3 weeks. They seem to do just fine.
I did have 2 hens, the first ever in over 15 years of raising chickens, that turned out to be Psycho Mom and Clueless Mom. One wouldn't quit trying to hatch them after they hatched. I think her instincts were faulty and she kept treating them like eggs, trying to turn them, etc., and every chick that hatched under her died. The other wanted to keep chicks under her constantly, and would peck them, -HARD!-if they tried to come out. Whenever chicks escaped from her, they hid in corners.
I removed them both, the chicks from Psycho Mom are with other hens, except one who was too afraid and he's in a brooder in the house, with a few others there wasn't room for with the hens. I pretty much maxed out all my hens with chicks. So the extras that would have been raised by the bad hens, I'm raising.