كيف أتصرف بمال حرام قدمته لأحد أفراد عائلتي، وقد تبت إلى الله وليس لدي المقدرة على رد المبلغ كاملاً، ولا أستطيع مصارحته بخصوص مصدر المال؟

If the money was acquired unlawfully, such as through Riba (usury) or gambling, then one must repent and dispose of it by spending it on the welfare of Muslims or giving it to the needy. Your giving it to your needy relative absolves you of responsibility, and you are not obligated to inform him of its unlawful nature. However, if the money was obtained through theft or usurpation, it must be returned to its rightful owners, based on the hadith: "The hand is responsible for what it took until it returns it." Then, you should compensate your relative if he has no right to it. Charity alone is not sufficient without returning the money to its owners.