Is your little hen broody? You'll know if she's flattened out on eggs, not leaving the nest more than 5 min/day, and squawking at you when you fuss with her nest. Then there's broody poop. How one small bird can make such a big, smelly mess?!
If she has all those indicators, then you should be able to make her believe she hatched the chicks. It takes a little time and sneakiness on your part. If she's sitting tight on eggs (or fake eggs or golf balls, etc), slip one out and slip a chick under her. It's easiest when dark because both hen & chick are just resting. Hen stays in her nest and young chicks stays under hen to keep warm. Keep checking frequently and if it's going well, keep slipping eggs out and add a second chick in 1-2 hours. If you think the hen is doing well and bonding (You'll hear her "talking" to her chicks) then you can move the hen and chicks into the brooder. Night time works great. Slide all the chicks under hen. When she wakes in the morning, she'll think she's been there the whole time and after spending the night together, there will be some bonding.
The main reason for doing it gradually is to make sure there's no aggression. It can be confusing for a hen to transition from sitting on eggs to raising chicks. It takes about 24-48 hours for a clutch of eggs to hatch and for a hen to transition and leave the nest. Once bonded, the hen will willingly move to wherever you put the chicks. However when she's sitting on eggs, a sudden change - like a fully fluffy chick running around - may freak her out and cause her to think the chick is an intruder. Her hormones tell her to protect her "babies" which have been eggs up to this point. In most cases of broody aggression towards chicks, it's because of that protection instinct and the integration needs to be slowed down or the hen has not been broody long enough to make the switch. Newly hatched chicks sleep a lot and don't run around those first few hours. The hen & chicks feel and hear each other before they "see" each other. That's why night/darkness/ will help a both hen & adopted chicks relax - quality cuddle time - as they bond. Hope this makes sense.
It's definitely worth trying if your hen is broody, because it's far easier to have a hen do all the work!. Broody-raised chicks may not be as human-centered as ones you raise in a brooder. Yet, they are hardy and learn chicken life skills earlier (scratching, jumping up onto things, roosting at night, predator awareness, finding treats in the yard, etc). Plus, Watching a hen care for chicks is so sweet.