Multiple or co-applicants

[Peter Morrissey]

I am ready to rent out my first BRRRR. Trying to figure out how to structure application and lease. It is a 2 BR in a two family. The applicant D, I have looks very good so far. Solid employment history etc. Checked Facebook. Looks fine. Still needs to fill out application which I am currently constructing. The examples I have, have a co-applicant section. In this case the applicant has a boyfriend with aparrently a good job and her mother with a job at a great employer. I believe D's income will be sufficient as she is a manger at Sears and the rent is 900.00. So who do I make the co-applicant?

Since there are two others over 18,I would want to have background checks done on them. Wouldn't I then have each just fill out their own application. 

Would D be the primary applicant?

Pretty sure I would want each one on the lease so they would all be responsible to make sure the rent is paid if one leaves. Just a little confused about how to set that up, and how to handle it with the applications.

Thanks,

Peter M.