Is expiation (kaffara) obligatory for someone who intended to fast after the break of dawn, then made up that day five years later? And is it obligatory to inform one's sister about the necessity of making up the fast if her intention was hesitant, like that of the questioner?

For the validity of an obligatory fast, the intention must be formed during the night, based on the Prophet's (peace be upon him) saying: "Whoever does not make the intention to fast before Fajr, there is no fast for him." Thus, if Fajr dawns upon someone while they are hesitant about fasting, their fast is not valid and they must make up for it. Expiation (kaffara) is not required in this case; rather, it is only required for a resident who breaks their fast during the daytime in Ramadan (definition) solely through sexual intercourse.