If the deceased had a credit balance with a utilities or other company before they died, that credit may be put towards paying the first or subsequent bills after their death.
To illustrate this in Probate Plus, do the following:
1. Record the credit as an asset
2. Realise that credit into a cash tracking account called something like 'Credit with gas company'
3. Record a bill which arrives as a liability/ admin expense (depending on when it was dated).
4. Use the credit in the cash tracking account to pay off the bill. If the credit only covers part of the bill, then split the expense and pay the balance from whichever source paid it in real life.