I wouldn’t know about reintegration in a flock of three, but since she’s only been away since Monday/Tuesday, they might just take her back in and she might not have troubles with the temperature. I had a hen a few weeks ago who got ripped open down the side, and she was in my basement for about two weeks. I cleaned her up, applied triple antibiotic ointment, and bandaged her skin flap back on. I gave her food, water and a nest, and left her on a tarp for easy poop clean up. On the second week, she began walking better and laying eggs again. At the end of the second week, I decided there wasn’t anything else I could do for her— my parents didn’t want a chicken in the basement and the chicken was probably Lonely, so I moved her outside to the chicks enclosure (now integrated) with food and water. She stayed in the chick run for a total of five minutes, then broke out and joined all the chickens. Other than a scuffle with the guineas (who want to scuffle with everybody) she just walked over and retook her place. I’ve got a dozen free ranged chickens, so maybe they just didn’t notice??? Anyways watch when you let her back out, because the rest might not even mind her return (they might even miss her!)