For FED read 7-1-1, NOTE:
You should have left B4 at 3rd and kept B5 up... Essentially when an improper batter is on base and the defense finally recognizes things, you pick up with the order with the proper legitimized batter, except if he's on base then you pick up with whomever follows him. If that batter is on base too, then whomever follows him or perhaps more easily whomever follows the "highest number order batter on base". One would hope you don't get too far down the order before someone notices; otherwise things get really crazy. IIRC, the MLB rule is similar - I'm just too lazy to walk to get the rulebook.