@Patricia Steiner we were actually under contract and using a bridge loan.

If they go under, your sh!

You can set up an LLC after you've gotten under contract on a deal!

Licensed with permits ~$3,250.HWT standard gas single family low efficiency without exhaust retrofit $900.Sand and stain hardwood floors, natural stain $3 per sf.Paint interior walls, ceiling trim and doors 3 tone paint scheme 2 coats $3.20 per sf (floor area cost includes paint)Click lock LVT flooring install overlay inclusive of prep and quarter round $4.50 per sf (materials and labor)Asphalt roof installation 3/1 - 800 sf bungalow with 2 layers of shingles - ~$7,900Standard porch cap replacement with 2 new precast concrete steps ~$2,500Used stove or refrigerator delivery and install $350New stove or refrigerator delivery and install $HD model specificUse this as a general guideline. 

The family purchased a lakefront property in a nice area three years ago but then ran into a series of issues, and have abandoned the place because of them.They are hoping the bank allows a short sale (asking for roughly $20,000 under what is owed)Here's what's made them so unhappy:Anytime they used the laundry it was dumping into a dry well, which would back up into the house forcing them to take their laundry to a laundromat instead!!

Also, focus on 2 years of job/income stability.Class D Properties:Cashflow vs Appreciation: Typically, all cashflow with little, maybe even negative, relative rent & value appreciationVacancy Est: 20%+ should be used to cover nonpayment, evictions & damages.Tenant Pool: majority will have FICO scores under 560 (almost 30% probability of default), little to no good tradelines, lots of collections & chargeoffs, recent evictions.

At one time I had over 2000btc, sold a great deal when while was under $100/btc to start my rental business.

Are they way under market, or is it manageable for now?

If they do, you may have a chance under the scenario you're proposing - if they share your concern for it's condition (although that seems unlikely since they've been living with it the way it is for some time, it seems).If you own it, it's pretty lowbrow to expect a neighbor to invest in your property. 

I’m under contract with my latest flip, the proceeds of which will pay off the heloc that I use to buy and rehab properties.