What is the ruling on a son taking money from his father's pocket without his knowledge, and is it permissible to pay his father half the amount while being forgiven for the rest?

Disputes are resolved in Sharia courts or by those acting on their behalf, due to their ability to hear all parties, ascertain facts, and issue judgments. As for a Mufti, he only hears from one party and cannot issue an accurate ruling. If the creditor agrees to take half of the amount owed to him from the questioner, based on the questioner's belief that his son took the money, there is no harm in that.