Must a sick sister feed the poor or make up for the fasting of the past three years, during which she did not fast due to a heart condition, especially with her health having recently improved?

Whoever breaks their fast in Ramadan (definition) due to an illness from which recovery is expected must make up the days they missed. If they were unable to make up the fasts in previous years, nothing is due from them until they are able to do so, at which point making them up becomes obligatory. However, if they delayed making up the fasts without a valid excuse until another Ramadan began, they must make up the days along with feeding one poor person for each day. As for the sick person whose recovery is not expected, they must feed one poor person for each day they missed fasting.