I was not debating the right of B to come back into the game. That would be based on if the covering official thinks. I am just saying B has not fouled yet by rule.

I do agree with the rest of what you are saying. ;)

Peace

You are still missing the point. B can go out of bounds and return legally anytime before a change of team possession. Rule 9-6-1 specifically refers to A & K.

The penalty for IP would be against A if he steps on the sidelines while making the illegal block and then his next step is in-bounds. This would be a multiple foul against A and I'm sure B would take the 15-yard IP rather than the 10-yard BIB.

NFHS Rule 9 Sec 6
 

NFHS Rule 9 Sec. 6 Art. 1... Prior to a change of possession, or when there is no change of possession, no player of A or K shall go out of bounds and return during the down unless blocked out of bounds by an opponent. If a player is blocked out of bounds by an opponent and returns inbounds during the down, he shall return at the first opportunity.

NFHS Rule 9 Sec. 6 Art. 2... During the down, no player shall intentionally go out of bounds and return.

I humbly stand corrected on the issue of B intentionally go OB and coming back in. Thank you.