There was recently another poster on here in a similar situation.
If she really is going broody, then she has given you a great opportunity to add to the flock of one!
Letting her raise chicks on her own is likely to be much smoother in terms of integration, as opposed to introducing juveniles to her. It’s also safer (usually), from a bio security standpoint.
She will not need any other members to be content, if that is what you’re asking. She’ll be preoccupied with caring for them while they’re young, and should mingle with them quite peacefully once she stops mothering them.
Now the question is, if you want a broody.
First you’ll want to know if she’s actually committed to the part. The test for most people is if the bird in question spends two or three consecutive nights in the nest. A lot of mine are nest sleepers, so I try to observe their commitment and behaviour throughout the day as well.
Another thing is, you might not know the gender of the chicks. If you’re planning on placing sexed day old chicks under her, that will not be much of a problem.
If you’ve decided that the broody is the way to go, then you will need to wait some more.
While every broody is different, and even the same hen might differ in behaviour from one brooding cycle to another, giving day old chicks to a fresh broody isn’t a good idea; it’s likely that she’ll reject them.
I would wait as close to the 21 day mark as I could, counting from the day she starts sitting consistently. Keep dummy or infertile eggs under her so that she doesn’t break (the latter might break and make a mess of the nest, so what of the two you choose is up to you).
After that time has passed, she will naturally be expecting chicks, and is likely to be much more receptive of any that get placed under her.
Unfortunately, we or you can’t predict with absolute certainty how she will act until you try it. Most of the times it goes very well, but I have had it go bad.
If you decide not to let her sit, then yes, integration works quite similarly. After quarantine is over for the juveniles, place them in a separate area, where they are able to view but can’t touch eachother. After about two to three weeks (that is what works best for me), let them have supervised interactions. I do not expect any mature hen to be extremely friendly with a teen, but as long as they tolerate eachother, and none get hurt and/or bullied, it is usually fine. Make sure to have more than one feeding and watering station available, so that the newbies don’t get bullied out of eating.
Good luck!