Chick won't mingle

[Momsbusiness]

Hi posted this on another thread with no response. Hoping for some feedback .
I let my broody hen hatch some eggs this spring as a little project. Unfortunately a newer egg got left behind in gathering so after 3 hatched, and that day I unexpectedly adopted a baby chick that was alone from a store. Momma and chicks all accepted her and life was good for them. The other forgotten egg took 10 more days under Momma to hatch. The momma was fine with the age group and the new addition, but after time I eventually put momma back out with the older chicks.
The chicks all did well still but the youngest-Itsy Bitsy, has always gone off alone.She is healthy it seems but never really mingled. There is a 10 day difference but that does not seem like it should still be the issue after 9 weeks with her.
I recently put them all out doors, as it very hot here now. They are in their own little coupe, and she still is left alone or goes off alone. Tonight all the others had all gone in to roost and she was laying outside in their little yard alone sleeping.
I picked her up and brought her in the house to stay in their old brooder.
She loves to be snuggled and is sleeping on my shoulder ad I write.
What should I do??

 

[DobieLover]

Please post pictures of their housing and the birds in question.
They are not chicks any longer. They are pullets and cockerels. Hormones have started to flow.
She is likely avoiding the others because she is at the bottom of the pecking order.
They won't fully integrate until all are laying. Until then, they need extra space.

 

[azygous]

As long as this chick is healthy and behaving normally, leave it be. Often, a chick that is a lone chick of a hatch will be independent. There's nothing wrong with that.

However, you need to observe the chick with the others to be sure it's not being picked on as the reason it doesn't want to sleep in the coop with the others. If it's not, simply put it inside when evening comes.

 

[JacinLarkwell]

Likely the separation started at hatch. I've had age differences of 3 or 4 days and that's enough that you can usually tell who was last until they're over a month old just by actions