I leave mine with the flock. She can go out into the flock as needed for eating, pooping and drinking needs. I will remove her from her nest carefully about every 2-3 days - just to check the eggs making sure that she does not get some stray eggs. The ones she is setting on are marked.
I do not bother her at all the last week. I just ignore her. She knows where the water and feed is, and will take care of her needs.
I will check (who can resist) when it gets down to day 20-21 to see if I hear peeping, but I stay out of the coop and let her be.
The next day, I will set up water and feed on the floor of the coop. But I just wait. Usually within 12-24 hours, after I hear the first peep, I will go down and she will have them out of the nest. The layers are used to leaving her alone. She introduces them to the flock.
Within a week - they are running in amongst the layers, and are mostly ignored. Yesterday - I have one with 3 chicks, and when I went down to the run, she had 2 of them up on a platform about 2 feet off the ground. I will put a board across the roosts. In the past she has had them roosting with the flock by week 4.
Mostly, they know more about being a chicken, and if you leave them alone they will tend to it. But not every chick lives.
Mrs K