Bracket (aka Miss Neurological sat and hatched three chicks with her two sisters last month. I had some reservations regarding this cooperative sit having had problems with double sits in the past. There were disadvantages which I won't go into here, but the end result was three healthy chicks with three mums. The chicks show no mother preference and apart from Bracket trying to boss everyone about the six of them are out and about free ranging as a group.
So far they've made their way to roost a bit earlier than the others and I had a couple of evenings of assisting the chicks on the ramp into their coop. I check each night to make sure all the chicks are there. All three hens and the chicks tend to sleep in one small nest box in a pile.

I often check all the coops before I go to bed and I've looked in on Tribe 2 as I've done this.
The first couple of times I've checked the mums and chicks late at night, as one might expect, all the hens are alert before I've opened the door.
On night three it finally sank in; Bracket's head wasn't thrown back. She was sitting in the pile looking perfectly normal. Just sitting would in the past make Bracket throw her head back and trance.
While she was incubating the eggs she had her head thrown back. You could pick her up and her head would stay in that position until you put her on the ground, yet there she was fully alert and looking normal just with a door opening.
I've checked at various times and she looked normal every time.
In the short term at least Bracket is fixed!
It could be she doesn't sleep the same way while she's got the chicks under her. It could be that the hatching and now care have switched something on or off in her head. It could be a number of things and hse may go back to her head throwing once she stops caring for the chicks.