Don't interfere at all. We (humans) do not understand enough about chicken politics and chicken behaviour in general to make the right decisions.
Soooo... Yeah. I think I'm just gonna stop reading all of these other posts about killer roosters and how to build airlocked fortresses to separate broody hens and "look don't touch" etc. Like you said, in a coop/run situation, methods will differ. But reading these alarmist posts is clouding my natural inclination to believe that, given space and a modicum of good sense on my part, the chickens will work it out.
Yesterday, Tina and her brood came out to range as usual and I put Patucha and Solo in a mobile enclosure under the plant nursery roof (it was drizzling). At about 10 am I noticed that one of Tina's chicks was limping a bit. The terrain is really uneven here, there's lots of drainage trenches the chicks have to jump and tree trunks on the ground etc, so I've seen this before. Always with a day or two of more restricted movement, the chick has recovered. Mama has been taking them all over the place every day -- even into the forest, so a little break for them is fine.
So I switched things up and put Tina's three chicks in the enclosure and give Patucha a chance to parade 12 day old Solo around for the first time.
But I left Tina outside the enclosure. To see what would happen between the two moms if they were both unconstrained at the same time.
What happened? Absolutely nothing. Patucha took Solo over the nursery and the two moms and the all the chicks spent the whole day in the same area, staying dry, digging in the leaves and having a grand old time. By the end of the day, the slightly injured chick was putting weight on both feet again. I let Tina's chicks out of the enclosure and they all walked back to the coop for the night together.
Tina on the right of her three chicks inside the wire. Patucha and Solo a few feet away in the back.
This morning Lucio was hovering around little Solo. Patucha clucked and puffed, but I'm pretty sure Solo got imprinted.
Little Solo, stretching his legs outside.
A good day. And Frida, the new pullet, is now friends with Cleo and Dusty.
Cleo, Dusty, and Frida, chilling together.