Abu Yusuf and Muhammad do not regard exiting by a voluntary act as an additional fard. Once the last sitting is completed, the twelve events do not negate the already completed obligatory prayer.
Opening interactive controls...
The two disciples: fard completes with final sitting
Hadath during Prayer: Building, Restarting and Twelve Final-Sitting Cases
Abu Yusuf and Muhammad do not regard exiting by a voluntary act as an additional fard. Once the last sitting is completed, the twelve events do not negate the already completed obligatory prayer.