Penalty enforcement...

[Mike51]

NFHS

Bear with me on this one. 1st and ten from A twenty.QB is back to pass, his facemask is grabbed and twisted by B44. QB somehow does not go down and is able to complete a pass to A88, who is tackled after a 25 yard gain. Can the 15 yard penalty be added to the end of the play? Am I correct in ruling that since it was a loose ball play, the enforcement spot is the previous spot and accepting the foul would result in less yardage for the offense.

If so, then what about when a QB is sacked for a 10 yard loss and the Defense commits a 15 yard face mask penalty. This is a running play and should be enforced from the end of the run, right?
One more kink, if the QB were to fumble while being tackled and his facemask is pulled, then we have a loose ball play and enforce it from the previous spot, right?

I apologize in advance for being long-winded.