[cowbyfan1]

Here is what I am getting after looking into the more and more. It is being looked at as a non player foul since the sub ran onto the field after the snap and did not interfere. Last year when it was called an IS it was 5 yards from the basic spot (sucseeding spot). This year it is called an IP and carries a 15 yard walk off from the basic spot. The Fed is still looking at it as a non player type foul tho and that is why 9-6-b is saying what it is.

ref rule 2-30-10 a NON PLAYER is a coach, trainer, other attendant, SUBSTITUE, OR A REPLACED PLAYER WHO DOES NOT PARTICIPATE BY TOUCHING THE BALL, HINDERING AN OPPONENET OR INFLUENCING THE PLAY. SEE 9-6 FOR IP.
rule 9-6-4-a IP when any player, replaced player or sub enters during the down.
rule 10-4-5-c The basic spot is the suceeding spot for a NON PLAYER foul.

So in this case, even if a TD is scored and you have this flag the ball will marked off on the try or suceeding spot.

The case of the multiple players coming on the field and blocking B players would be a Multiple foul case for each player coming off the sideline and B would get the choice of where to mark it off from, which in the case would be the spot the most distance from the goal line (which may or may not be the first player to enter and get involved).