Is it permissible to change one's intention from a general charity (sadaqah) to an expiation (kaffarah) for feeding the poor due to fasting, by adding a previously designated amount for charity to a new amount to complete the value of the expiation?

Intention (niyyah) is a condition for the validity and acceptance of acts of worship. Its time is at the beginning of the act of worship or a short time before it. As for intention made after completing the action, it is not considered and does not validate the action. Therefore, the intention of a charity (sadaqah) cannot be changed to an expiation (kaffarah) after it has been given, and the expiation remains an obligation. It should also be noted that the fidyah (expiatory feeding) for one unable to fast is given as food, not money.