I don't know what else to say but this.
No where in 7-2-D (2014) does it say at the time of the appeal. It says when BOO is discovered.
In the original scenario of this post we have B2 on 3rd, B1 on 1st. We have B3 at bat and s/he has received a pitch.
The BO was reestablished once B3 received a pitch with B2 on base so there is no BOO to
discover .
I think this is what is not being understood
As far as figuring this out on the field. That's what we get paid to do.