Where seller finance contracts may be adjusted is when terms are not at reasonable market rates or where a conventional purchase would allocate much less toward the debt or purchase price.

You have to decide whether to account for it as debt or equity.Either way, it goes into the LLC bank account.

Any recourse that the senior lien holder had is toward their defaulted debtor.

If you need cash flow, buy high performance debt or Tbills.

Many banks, for example, are fairly comfortable with cleaning out a foreclosed home since: (1) most of the stuff is likely rubbish; and (2) the fact that the debtor ended up in a foreclosure likely means they have no money, which in turn means that they can't hire a lawyer to fight a national or regional bank. 

The best way to ruin your relationship is to become debtor/debtee.  

In that case, a capital partner on the debt or equity side may be a good partner.You probably have a bit of time to commit to your goal, and you probably have the discipline to stick to a plan.

Use leverage for Rehabs in order to build cash reserves to then buy more rental properties with very little debt or no debt...  

Or does the new owner assume that debt? Or

Maybe a partner signed for the bank debt or I took a property subject to that disqualified me.