I would make that move now while Mama still has those protective broody hormones going.
As the chicks get older, she will be less protective, meaning the babies will have to fend for themselves when you integrate. Do it when they’re young and they will have already been accepted by the flock when she weans them. That will make their lives a whole lot easier.
Your chicks have the advantage of Mama protecting them. Makayla’s didn’t. Reading back, it also seems the birds were a bit crowded. That will also cause problems.