Visit Visa How Many People?

We are a family of 7 people living in one house. I recently got married abroad and my husband lives with us.
My parents wrote a letter in our spouse application stating we could live with them rent free and we still do.
My dads nephew wants to him to sponsor him on visit visa. Can he sponsor him while my husband is living with us on spouse visa?
My parents dont pay tax and are on benefits.

Also this newphew has been in the Uk previously on student visa but had to leave when his visa expired. He now has US student visa.

Also see Part X of the Housing Act 1985 to see if you are living in overcrowded accommodation.