Do realize that your sweet hen is going to attack these babies. Your babies can go into the run and coop, but they need a safety zone. A place they can escape too out of her reach. Pallets, lattice panels or wire fencing slightly off the ground can make a barrier the chick can go through, that the big girl cannot. Set that up, inside of it, set up box or a tote on its side, so the chicks can get out of the wind and weather, put the wooly hen in that.
I am my second year on the wooly hen. You just need good deep bedding on the floor, and some good insulation on top. I have used, a goose down vest, an old cheap pillow, and my first attempt of wool. Attach the insulating piece, so that it is about the height of the chicks back. Make sure they can get out two ways.
You will have to stick them under it at first. I would turn out the lights, they would peep madly, then stick them under there. It should get quiet. And they will go to sleep.
Mrs. K