Might consider a huddle box for the newbies.
Were they outside but with a heat lamp available?
Just how 'heated' were they?
What about integration with your other birds?
Wrote this is for chicks, so adjust to your situation:
Make them a 'huddle box', put it in the brooder after turning off the heat(you might have to 'persuade' them to use it) then move it out to the coop with them.
Cardboard box with a bottom a little bigger than what they need to cuddle next to each other without piling and tall enough for them to stand in.
Cut an opening on one side a couple inches from bottom and big enough for 2-3 of them to go thru at once.
Fill the bottom with some pine shavings an inch or so deep.
This will give them a cozy place to sleep/rest, block any drafts and help hold their body heat in.