I don't know what you can do, I have a similar situation with my wee tootsie, she's a stunted wee thing and only half the size of my other hens who try to rip her apart if I lock them in the same overnight coop, the banging and squealing of her trying to escape breaks my heart to hear when I've tried putting her in after dark and shutting the door. I eventually added an extension to my coop and run, basically joining on a smaller coop at one end. she now chooses to sleep in there on her own. I'm not sure it's the correct solution but she seems much happier and gets a chance to sleep in peace even if she might be lonelier. I'm not sure what I'll do though when it comes round to winter as I'm worried she'll freeze in there on her own as it's lower to the ground and without a fully closing door, probably great in this hot weather but not so good if it turns wilder.
