My tenant is asking if they can have a guest in the house for 4 months

[Sohrab Khosravi]

Hi BP nation,

I have a question about one of my rentals. I rent a 4 bedroom house to 3 collage student in the past. They also have a cosigner on file. Last week, they asked me that one of their family members visiting from Denmark for the summer for a school program, however, he is not happy with a family he was placed with. Since they have an extra bedroom they asked if he can stay with them and he will be there until the end of august.

Now I want to know what should I do let him stay. Do I need any paperwork.

To be honest, they could just ask him to come without telling me and hope we do not find out.

Please help me with this problem.I know we have a lot of experienced land lord on this awesome website.

Thank you