Is it permissible for those who missed part of the prayer (masbūqīn), having caught up at different points, to put forward one of them who caught the first rak'ah to lead them after the Imam's salām, especially if some of them have invalidated their ablution?

Scholars have differed regarding the validity of praying behind someone who joins the prayer late (masbuq). The preponderant opinion, and the one we issue fatwas according to, is the validity of following a masbuq in prayer. This is the view of Sheikh Abdul Aziz bin Baz, may Allah have mercy on him, who stated in his fatwas that the masbuq intends to lead the prayer, and there is no harm in that. Al-Dussuqi al-Maliki mentioned the permissibility of someone leading the prayer who joined less than a rak'ah, and that he intends to lead after having intended to be a follower. Similarly, the Shafi'is and Hanbalis permitted transitioning from one congregation to another due to an excuse, such as in the prayer of succession (salat al-istikhlāf). Therefore, what these people did is permissible, and their prayer is valid. However, it is preferable to avoid it, as it was not commonly known among the early generations (Salaf).