[CecilOne]

If the batting order is "straight nine", no DP, DEFO, DH, or EP and someone not in the lineup bats, she is an unreported sub. Unless there is a specific interpretation issued for DEFO, that proves that what I said above is wrong and the only usable approach is that the DEFO is an unreported and illegal sub for B1 or whoever was due to bat.

I also agree with Dakota's comment that "if DEFO gets on base, and a pitch is thrown, then go from there with DQ's and BOO's, recognizing that at that point, the DEFO's "at bat" is now legal, even though the DEFO herself is not. Therefore, B2 is due up, not B1.".

Also, if the protest is made before the pitch is thrown, the DEFO is DQ and must be replaced. My other mistake above is that the DP can not replace the DEFO at this point because it's the wrong batting order spot. And B1 would be an illegal reentry into the B2 spot, so B1 is also DQ.

I also agree that it's not BOO for the DEFO because the DEFO is not in the "batting" order, unless she has reported as a sub for the DP.

Another question: if the DEFO is replaced by a new player, does that continue or terminate the DEFO role? It seems to me it terminates because the new player is in the B1 spot.

I dread the next NFHS season when 45 states worth of "gym teacher" coaches begin using the new rule.