Introducing chicks to flock

[little kiwi]

Hi, We have a medium sized mixed flock. One hen is in a seperate enclosure with 2 chicks of about 5 weeks old. In another enclosure we have a frizzle hen with her 10 chicks of about 4 weeks old. We also have 2 chicks under a heat plate from the incubator that are about 3 weeks old. Especially the hen with her 10 chicks are quickly outgrowing their space. Can I somehow put them all together in a larger space or are the 2 mums gonna fight and kill each others chicks and/or the incubator ones? When and how should we introduce them to the flock (including big hens like Wyandotte, light Sussex and shavers)?
Thanks for your help

 

[ChickenCanoe]

You may be worried about the wrong things. It is extremely unlikely the two mothers will attack the other's chicks. They don't do that. Their main concern is protecting their own chicks from all comers.
The best time to introduce chicks to the flock is as soon as they can walk. The longer you wait, the greater the chances that the mother will no longer care about them. Your concern is the chicks with no mother. I would introduce those chicks to the hen with the two chicks first for a couple days till she adopts them. Once they are a team, put All together. After a bit of the mothers letting the other birds know that they better not hassle the chicks, eventually the chicks are accepted as members of the flock. There will always be squabbling as birds perform the pecking order conflicts to vie for hierarchy.