Last play penalty question and enforcement

[Texas Aggie]

Putting aside that 6 on the line is no longer an NCAA foul (we'll just substitute it with 5 in the backfield, since that isn't the issue here), the NCAA ruling is pretty much the same. The way to approach this is to tell B that they have 2 ultimate choices: either there's an untimed down with A keeping the ball (offsetting fouls) or the quarter has ended (declined penalties, making what happened stand). If they want to know why, I'll explain, but no rational A coach is going to let B take an untimed offensive play when they can avoid it, thus the question of whether to accept or decline (for A) is obvious.