Lease option buy-out, and unaccounted tenant

I have, what seems to be, a great starter opportunity. This will be my first large deal, so I'm scared, to say the least.

Property info:

- Off-market

- 3/1

- ARV ~$90k

- Reno Est. = $30k

- Cash price $32k

- Old Singlewide on the additional acreage (salvageable, but not worth the effort)

Pros:

- livable (two current tenants)

- additional septic/utilities could be additional income (ADU)

Cons

- one previous tenant passed away in the home

Here's the kicker, at least to me, the current owner is under a lease option contract with the current tenant. The tenant is the one trying to sell the house, which is technically similar to a wholesale deal. They are contracted to purchase at $X, and they want to sell at $XX.

I've never heard of anyone doing this, so I'm curious if this is something that's legal?

To add to the complexity, there's a retired lady living in the house (a friend of the lady that died in the home), who isn't listed in the lease. This scares me a bit, in that she might could pose a little hiccup in getting her out. I have no reason to believe she'll be an issue, it just bothers me.

So, all that said, what's your advice?