What is the legal ruling on making up missed Ramadan fasts after approximately 12 years have passed since they were left due to postpartum bleeding (nifas), and is it obligatory to only make them up, or to make them up and offer expiation (kaffarah)?

Whoever breaks their fast in Ramadan is obligated to make up for it (qada'), and they may delay it until another Ramadan begins. It is not permissible to delay it more than that. If they delay it while having the ability and knowing the impermissibility of the delay, then according to the majority of scholars, an expiation (kaffarah) becomes binding upon them. This expiation is feeding one poor person one mudd of food (750 grams of wheat or rice, etc.) for each day. However, if they delay it out of ignorance or forgetfulness, then no expiation (fidyah) is due upon them.