Tenant got married and wants to add spouse to the lease

[Eugene Khoruzhenko]

I lease out individual rooms in a rental house. One tenant got married and wants to add spouse to the lease. The main tenant is okay - pays rent on time, agreed to pay extra for the other person, all looks good and the lease is for almost another year. However, screening of the spouse revealed debt, collections, no source of income, etc. - I would never accept that person alone. The main tenant now demands that we accept the spouse because they cannot live without each other, and will be totally responsible for the other person and full rent payments. On one hand, it is okay with us as long as we receive the monthly payments. On the other hand, I have a feeling that something may go wrong. Does anyone have a similar experience, what can go wrong? Normally I would add both on the lease agreement equally responsible for it, but in this case can I specify that the original tenant is the primary tenant responsible for all financial side of the agreement? What if they break-up and the primary tenant decides to leave, does it mean that the sub-tenant must vacate as well? Can the sub-tenant claim that they will stay and the primary tenant must keep paying as per the agreement? Are there any standard addendums or separate agreements that cover couples?