Moving chickens is very stressful on them. Is it that she is choosing not to move or is it that she CANNOT walk?
Pick her up and set her on her feet to see if she can even stand. If she can stand it could be she is terrified and trying to be unnoticed by the others. If she cannot stand there is certainly something going on.
When you got them did you see her standing and walking? Did you check them each over prior to getting them to make sure they appear in good health? If you did not see her standing or moving around but she is capable of walking is it possible she is a broody hen and is still in the broody catatonic state?
I am a bit concerned as they are not quarantined and could have brought a disease to your flock being so close together.
This link will take you to a very good article that explains it and why it is important.
It is common that people do not know how to or why to quarantine new birds. It is not something to panic about just yet. It is something to read up on and follow in the future. It is a shame when people bring in new birds and lose beloved older ones by not knowing.
Check them each over asap and look for any issues with her feet or joints that may make standing painful in particular.
I myself in the past when I did not know about chicken health and quarantining brought birds in and put them right in the coop. I was lucky none were ill.
Let us know what you find with her legs and feet. Lots of nice folks will be along I am sure to offer what knowledge they have and try to help.