Adding short term roommate

[Lacee Beitler]

Hi everyone! We have a large 4 bedroom that is currently rented out to 3 recent grads/ young professionals. They have been relatively quiet and good tenants. They recently asked if they could have a friend move in for the summer months. This individual moving in is a recent (under) grad looking for a place to live this summer while she is in between schools... she’s going to start grad school this fall. She went though the background check and checks out. My question is... how do you add her to the lease? We thought of an addendum binding her to the current lease for the months she was staying, but do all the roommates sign that? Would you do a whole new lease just for her, or make everyone sign a new lease? That seems like a hassle, but we want to be sure that the other 3 roommates agree to have her move in for a few months. Thanks!