I think that the 2 chickens more yellow colored are hens and the red one in the back maybe a rooster. I can't tell about the closest one because it is too blurry do you have a non blurry pic of all of them?
that sounds like something that happened to my lemon cuckoo niederrheiner pullet she was probably around 6 months and she couldn't stand up and she could only lay on her side she could still move both her legs and her wings and she sometimes even propped herself up on 1 leg and we kept her in a...
if your new chickens are bigger then your other ones the older ones will run away. I have 6 year old Barred Rock hens and I had 6 month old Lemon Cuckoo niederrheiner pullets and they are bigger then my barred rocks and the rocks were scared of them