What is the ruling on Fajr prayer if it is performed before making up for missed Maghrib and Isha prayers? Can missed prayers be performed after the current obligatory prayers, and are the Sunnah prayers affected by that? And can missed prayers be made up along with their counterparts on the following day?

The Fajr prayer is valid and does not need to be repeated if it was prayed before Maghrib and Isha due to forgetfulness. This is because, according to many jurists, the order between missed prayers is waived if forgotten. Hanbalis and Hanafis hold that the order is waived due to forgetfulness, while Malikis believe it is obligatory even with forgetfulness if it is within the time. In any case, the prayer is valid because, according to Shafi'is, the order between missed prayers is recommended, not obligatory. There is no obligation to maintain an order between supererogatory prayers. Whoever forgets a prayer must perform it immediately upon remembering it.