What is the ruling on a person performing a supererogatory prayer leading a person performing an obligatory prayer in the Maghrib prayer? Should the person performing the supererogatory prayer recite aloud if he becomes the Imam? And what should one do if he missed the first congregational prayer?

It is permissible to be led in prayer by someone who has missed part of the congregational prayer (masbuq). If someone enters the mosque after the first congregation has finished, they should strive to pray in congregation as much as possible. If they find another person, they should pray together as a congregation. If they do not find anyone, but find a masbuq completing his prayer, they should pray behind him. If they do not find anyone, but find someone performing a supererogatory (nafila) prayer, they may pray behind him according to the more authoritative opinion. However, if this person performing a supererogatory prayer is performing a regular sunnah prayer (ratiba), it is not legislated for him to recite aloud.