Must the heirs carry out the deceased's will to feed the poor to compensate for his missed fasting, and how much is the specified amount for that, and is it permissible to put the amount in a donation box for the mujahidin?

If a patient with a curable illness dies before making up for the missed fasts, there is nothing due from them. The expiation (kaffarah (definition)) should be given as charity from one-third of the inheritance if they had willed it. However, if the illness is incurable, the expiation is obligatory for each day, and it should be paid from the inheritance before its distribution if the person dies before paying it.