6 week old Australop chicks mounting mama hen

[NoNeck]

Hi everyone! I have 6 black australop babies who have been housed in a separate cook with mama hen this whole time. Lately I have been letting mama hen out of the smaller coop to roam with other hens as she seems eager to rejoin the rest of the flock. Today I realised when I put mama hen back inside, 2 of the chicks started jumping on the mama hen and one of them in particular jumped on and appeared to lay flat like a pancake on mama hen as if it were trying to mate with her?
Im new to raising chicks so i dont know if this is their way of establishing their pecking order. What threw me off is only one of the chicks did a weird motion and for lack of better words, tried laying on the mama hen or something. I am also unsure of the sex of all my baby chicks as they are only 6 weeks old.

 

[nuthatched]

Post pictures, they may be cockerels.
Or just trying to hide, though underneath is a more common area

 

[aart]

she seems eager to rejoin the rest of the flock.

She's ready to wean the chicks.....let them all out.
It's unlikely you are seeing 'mating' behavior, if that's what you're thinking.