Should my sister recite Surat Al-Fatihah and a [subsequent] surah aloud, or is it sufficient for her to listen when praying with me in congregation?

The preponderant view is that the ma'mum (congregant) should not recite Surat Al-Fatihah or any other surah (definition) behind the imam (prayer leader) in a loud prayer if he can hear the imam, based on the Almighty’s saying: "And when the Qur'an is recited, then listen to it and pay attention that you may receive mercy." (Quran 7:204). It has been established from a group of the Salaf (early Muslims) that the intent of the verse is to pay attention when the imam recites. However, the Shafi'is hold the view that it is obligatory for the ma'mum to recite Surat Al-Fatihah in both loud and silent prayers. To avoid divergence of opinion, reciting it is preferable. As for other surahs, the ma'mum should not recite them while hearing the imam, according to everyone. But if he cannot hear the imam's recitation, then he should recite them.