So lets say its in Overtime in NCAA. if B recoveres after A has possession then A would get the ball at the 25 for their possession. But if b fumbles and A recovers again then A's possession is over and B starts again at the 25?
I don't fully follow you, but here are the possible cases in overtime. Assume 1st and 10 from B-25 in all cases.
1. A fumbles at B-20, A recovers at B-20 and is downed there. Possession series not broken, 2nd and 5 for team A.
2. A fumbles at B-20, B recovers at B-20 (and advances to anywhere). Possession series over. Either team B wins, team B puts the ball in play from B-25 for their possession series, or go to the next extra period.
3. A fumbles at B-20, B recovers at B-20 and advances to B-25, B fumbles, A recovers at B-25 (and advances to anything up to B-0.1). Possession series over. Either team B wins, team B puts the ball in play from B-25 for their possession series, or go to the next extra period.