Negotiating Sell Price When Seller has Family Tenants

[Nik Doukas]

I just saw 2 great buildings on one lot, great house hack potential except for 2 potential obstacles. Backstory first, obstacles below.

The rear building has 2 beds and 1 bath with potential to add maybe a studio apartment as well. Currently the tenant (seller's son) uses the potential studio space as a gym (great setup tbh) and they've lived there for (3) years.

Front building has a HUGE 3 bed 1&3/4 bath apartment over commercial space (little office great for an attorney or insurance biz, etc). Front building has Garage built into the side of front building. 

Seller's mother was the owner and passed away earlier this year, she's looking to simplify and sell to avoid having to deal with being a landlord. Her 2 siblings have no interest either.

The rub is this:

-Buildings are priced really high for the area in the condition they're in ($315,000 together)

-Seller has her adult son staying in the rear unit charging him and his wife about half of market rent ($525 currently)

I am seeing my numbers work out (FHA 3.5% down, living in the vacant apartment above the office, still paying $500 or so to live there) around the $240k-$250k range. And that is still with raising the rear tenant's rent to market (~$1100).

I really like this deal, I can see it being a great long term asset, but I can't justify paying anywhere close to what it's listed for. I'd also hate to be the bad guy and jack up the rent on her son and daughter in law, I'm getting the sense there's still some conversations to be had within their family...

My question is this: How do I go about making my offer in the $240k-$250k range while still being respectful of the family history they have here? 

Thanks in advance BP