How can one compensate for shortcomings towards their deceased father and ask for his forgiveness, and does the father feel it? Should a separate charity be dedicated to the deceased, or is it permissible to intend for him to share in a charity with the living? Is it permissible for one to perform voluntary fasting and dedicate its reward to their deceased father?

Shortcomings towards the deceased father must be remedied by supplicating for him and seeking forgiveness for him during times when prayers are answered, by fulfilling his outstanding obligations, maintaining ties with his relatives, giving charity on his behalf, and dedicating the reward of acts of worship such as fasting to him. This will reach him, by Allah's permission.