Think about it, if a person gave you a mission to protect his family, and does not give you a time-limit. Then he later dies, the rewards will be kept by True Will, and you will not recieve it until you protect his entire family till death.
But what if they have children, then create descendents, then they continue the Bloodline. You would've signed yourself for an eternal guardian-ship.
That is, if you truly need the rewards. One could just let them die if they are not desperate and move on to other missions.
"You owe me 1 Faith Essence"
The system suddenly added as if it forgot. Enigma bitterly sighed and questioned in exasperation, "Are you still angry at me? You can't be this petty."
"Whose being petty? Like I said, giving you information for free is not my function. Deal with it mate"