Tenants want to move in Nephew

[Tyler Rowland]

My Tenants want to move their Nephew into their house. 21 years old.  They say he is engaged and has a good job and will be out in 3 to 5 months.  I am okay with it if the following things are done.

1. He fills out a rental application
2. He passes a background check and credit score
3. Has a Job. (last two pay stubs.)
4. The tenants sign a whole new lease with his name on it. 

 Is there anything that I am missing here?  Is there any feelings one way or another or experiences anyone else has had?  

We are house hacking the Duplex these tenants are in.  

Thanks for your input!