Re-affirming an obligation post-Chapter 7

[Sean M.]

Question about re-affirming obligations under a Chapter 7.  If a borrower has a mortgage and has cleared a Ch 7 bankruptcy, then makes a payment on the loan, have they re-affirmed the obligation, such that it now effectively not a chapter 7 loan?  Key questions are whether they then become personally liable again and whether I can contact them again?  

Second scenario, same questions, but this time the borrower has entered into a loan modification agreement.  

Thanks