The chick won't leave it's momma

[angidee]

I have a Cochin that hatched 3 chicks at the beginning of May. She booted 2 of them at an age appropriate time, but let the 3rd and littlest one stay with her. This 'little one' is now 20 weeks old and regular sized. The momma has been broody and has been sitting on an empty nest for a month. This chickie will not leave her side and she isn't doing anything to make it go.
Should I do anything about it? It wouldn't be such a big deal if the chickie weren't pooping in the nest box all day while he/she sits with her momma.

 

[Happy Chooks]

I wouldn't worry about it too much. It's a pain for sure on cleaning the nest boxes. Where does the "baby" sleep at night?

 

[NovaAman]

I had a hen go broody and one of her babies sat with her the whole time. I ended up putting the momma hen by herself in the broody coop and that broke the grown chick from being up mama's butt. LOL.