What is the ruling on clothes acquired through debt with procrastination in repayment and doubt as to whether the full amount was paid, and what should I do concerning the seller? Are my actions, while wearing them, permissible? What is the ruling on things acquired with money I secretly took from my father and brother?

We advise you to stay away from obsessive doubts. The clothes you bought on credit from the merchant, with his willing consent, are your property and permissible (halal (definition)). Wearing them has no effect on your actions. However, it is not permissible for you to delay payment to the seller if you find what you can pay him with after the due date, based on the hadith (definition): "Delaying payment by a rich person is injustice."

As for what you took from your father’s or brother’s money secretly without their permission, it is not permissible, and you must return it to them, based on the hadith: "On the hand is what it took until it returns it." This is unless your maintenance is obligatory upon your father and he withheld the obligatory maintenance, in which case your taking what you need is not theft, based on the Prophet's (peace be upon him) statement to Hind, Abu Sufyan's wife: "Take what suffices you and your child, according to what is customary."