Is it stipulated that charity on behalf of the deceased must be from their own wealth, or is it permissible for it to be from wealth gifted to them by relatives?

It is permissible to give charity on behalf of a deceased father with any money, and the one who gives charity will be rewarded for it. However, it is not permissible to ask people for money to give in charity on behalf of the father. Rather, the father should be honored through supplication and other means as much as one is able.