Difficult heirs, it's almost like the Hatfields vs. McCoys!

[Letitia Harris]

This seems like the right place to post, and ask for advice.   

I've found an abandoned SFR, and after over a year of searching, finally found the heirs. The house has serious back debt to the city & back taxes, but there's room for me to flip it, if I can get them on board.
There is BAD blood between the 4 of them, and I'll need them to sign a contract selling it to me, after we get their names on the deed (it's still in the deceased relatives name).   There isn't a lot of profit for them, but it'd be better than the nothing they currently have, a vandalized, sad house, and no clear title to it.  None of them can afford to pay the debts.   I'll be paying to get all of that done, taking it out of the purchase price.
So, what have you done to get heirs on the bandwagon, when 2 of them detest the other 2?   They have anger issues regarding how other relatives were treated, years ago.  
Help!