Unique situation Wholesaling arbitrage?

[Pamela Maduro]

Hello all! i have a very unique situation with a seller, that i need some assistance with.

The owner of the property would like to sell; he has it as a rental arbitrage and that guy is renting out the 3 units. He hasn't paid the owner in a few months and the owner doesn't live in the area.

I've almost got him to a price point that works however i cant get access to the house due to the arbitrage. He has not idea what the condition of the property is either. Im not to sure how to go about this and if a buyer is even going to want to deal with this issue. What do i need to worry about as far as tenets rights, the guy doing the arbitrages rights. Do i need to factor in potential lawyer fees to evict?