Tenant application requirements? What would you do?

[Peter K.]

So I have two brothers that submitted an application for a property: one of them qualifies based on the requirement, the other does not, he makes about $1000 net a month when the minimum is somewhere around $2400 net monthly income, but combined they bring in enough to meet the minimum.

My question is, can the other brother who is qualified be a "co-signer" even if he is going to be living in the same place? Maybe I'm using the co-signer thing wrong here but what would you do and what are your recommendations?