Inherited tenants in rental home

[Yengkong Sayaovong]

I have a chance at a duplex and a 3 unit home. The people who owned the home are my god parents so they are just handing it down to me.

Issue is that they have tenants in home already who sometimes pay on time and sometimes late a month. Sometimes they only give half the payment and will pay the next month. They have a lease but it was never enforced. The lease doesn't specify end date.

The rent is way below market as well. How do I go about this if I aquire the properties? My state law says I have to honor the current lease til end of term. But there's no specific end date.