My boyfriend split with his baby's mum 7 months ago now he is with me and she is on her own she is threatening to take him away to another city and threatening with the court we need to know what legal rights he has if she does this?

She cannot, by law or any other means force him to be with her. He may have to pay child support, but I think that would be just about it.

I think by "him" the questioner is referring to the child.
I don't know the laws, but I'm sure someone here can help you.
Stick around and keep checking back.
I think that your boyfriend should contact a lawyer that can help him protect his rights as a parent.

I would suggest to go have a free one time meeting with a lawyer about this, but as far as my experience tells me, I don't think she can just run away with the child legally.