I have one (yeah, just one, sadly) chick that was hatched out from a hen. (I had two, one died at 4 weeks old). I tried to seperate them at about 5 weeks, and they cried for each other so badly, I put him back.
I figure I'll just wait until they are ready to seperate - he still sleeps underneath her at night, although, now she is sitting back up on the perch the last couple of nights, and the chicks flies up and sits under her, LOL. It looks pretty funny.
Today she was in the nest box, laying an egg and ... yep, the chick was right in there, too, squeaking and chirping away the entire time. He wasn't under her, just kept climbing all over the top of her, tryign to figure out how to get under her. Methinks I have a "mama's boy" on my hands.
I'd just let them decide, if that is possible with your coop set-up. I expect eventually they'll wander different ways and you can move the chicks without so much trauma.
ETA -- I just got the pics to load (kid is eating the bandwidth) do you have them in a brooder cage still? You can probably turn them out with the rest of the flock - all together. The mama will protect them (BOY will she!! the expression "Mother Hen" is so often said for a reason, LOL.) I let mine out of the brooder cage when the chicks were a couple of weeks old. I just opened the door and let Them decide when to take the chicks out.
Peace -
Meriah