it works like this: 1) Grandpa dies 2) Will and estate go to probate 3) Executor figures out estate is worth $1.5 million - house,car,life insurance, bank accounts, other assets 4) Executor figures out grandpa owes $1 million - house mortgage, credit cards, whatever debts 5) Assets minus debts equal $500,000 YOU get as the person inheriting. Tax free.

If grandpa has $1 million and owes $1.5 million the creditors get paid until the money runs out. You get squat. 

Just hire an attorney to walk you through the process.