Should one wait for the congregants who have not completed the obligatory prayer, or wait for the establishment of a second congregation, before performing the funeral prayer?

It is sunnah to hasten the preparation and burial of the deceased, just as it is encouraged to have a large number of people pray over them. If there is no fear of the body changing, then it is better to wait for those who are late or absent to increase the rows and supplication for the deceased. However, if there is a fear of the body changing, then no one should be waited for if a congregation is available to pray over it. It is better for someone who arrives late to prioritize the funeral prayer if they fear missing it, and then perform the obligatory prayer as long as there is ample time. It is permissible for someone who did not pray over the deceased to pray over them after the first prayer, and repeating the prayer over the deceased is for those who did not pray it, not for those who already did. Furthermore, two congregations praying over the same deceased in one mosque is not considered a repetition of a single prayer.