how do I keep them warm?

[aart]

Incubated them.
Yeah I have 4 others, one will have to be rehomed soon.
This is why I built a new coop- I can't resist when I see a broody (I feel bad if I have to break them)

Sounds like a clustertangle of an integration scenario.

 

[MadamContrary]

Your incubator chicks stay inside with heat so they are fine?
Draft free and ventilated coop? Yep, your broodies with chicks will be fine, constant supply of high protein chick starter available and fresh clean water close by for them? And your others will all be fine too. They are wearing coats
I've heard cracked corn snack before bedtime may help boost warmth? Or was it something else?

Meal worms also help raise body temperature and are a good bedtime snack in cold weather