Treat the mother and boyfriend as totally separate unauthorized occupants and let them know your process for getting them approved, or to vacate.Then document all your attempts to get in contact with the daughter and collect her rent.

Definitely collect enough info to make a good decision, but don't let your desire for more information keep you from making a decision. 

Hello, hope you are healthy and safe.I'm very aware of section (s.) 212.02(12), Florida Statutes (F.S.) which states ALL money collected from a tenant in a Commercial Property is considered rent and as such it's subjected to Sales Tax (5.5% + 1% Miami-Dade).I have a BIG objection with this statue.

I want to minimize showings only to people who are serious and weed out those who just want to browse and collect information from me.

He has a woman he pays $60 a month to collect the rent and check on the property and he knows a contractor in the area that does his repairs.

A few days later, we collected the lease for the current tenant and came to find out that the rent is only $850, with a $150 pet fee (3 pets at $50 each).

She has no guarantee of collecting this money in the future.

I know of at least one "lender" that made a living collecting fees and never making a loans.

Should you ask the seller if all tenants are paid up, what their April, May, and June rent collection totals were, and whether any tenants are having COVID-19 related employment or income issues?

You may also need to remind them on the importance of paying rent during this time, that their rent is still due (and potentially collecting interest depending on where the property is and what's in your lease), and trying to motivate them to start paying you back now.