Must a girl who broke her fast during Ramadan when she was fifteen years old, due to extreme thirst, and then ate after drinking, make up for the missed days (qada') or offer expiation (kaffarah)?

If thirst reaches a level where one fears perishing or severe hardship, and then breaks their fast, they are not obligated to refrain from fast-breaking activities for the rest of the day. They may eat and engage in marital relations, and there is no sin or expiation upon them.