Am I obligated to maintain ties with my father and brother despite the many disagreements and problems with them?

The father's right over his child is immense, and showing him righteousness and accompanying him with kindness is obligatory, regardless of his state or misdeeds. Repent to Allah and return to maintaining ties with your father. Avoid provoking his anger, be patient with his misdeeds, strive to treat him kindly, supplicate for his rectitude, and seek the help of wise individuals to influence him. As for your brother, you must maintain ties with him, and it is impermissible to abandon him.