Pasted together incomes from five people?

[Randall Beltran]

I was screening possible tenants in Nevada for a house, and I got a call from a group who all had very low income and loose-ties.

A woman and her 2-month boyfriend, plus three other friends whom they didn't know super well.
The group didn't meet my minimum income criteria unless ALL of them pasted together their incomes.

Because of the loose ties, and barely meeting the income criteria, I felt a bit worried if 1-2 people move out (1 friend, or 2 people because boy/girlfriend), because the remaining folks may not be able to pay the rent. (In my case, none of them met the credit criteria so I was OK rejecting on basis of credit - But if this wasn't the case, I'm not sure how to properly handle such situations?).

How do you folks on the forum normally handle these situations?

Do you put a limit on number of [tenants // lease signers // qualifiers] who can be pasted together to meet your minimum income criteria?
Do you ramp up your income criteria based on number of signers? (E.g. 3x income/rent ratio for 1 person, 4x income/rent ratio for 2 people, so forth?)
Have you never seen this before?

Anyways, I'm pretty new to this. Hoping to get some advice from all the great sages who lurk this forum :)