Could be anybody! Sugar, Mike the security guard, a relative of Sheila's, some unknown entity. I don't see why B&B has to suffer because of Y&R's ridiculous plot developments.
Several years ago on OLTL, a major character (Victor Lord) came back to life in a horribly written, poorly executed and atrociously acted storyline. A year or so later, after the dust had settled, a character had referred to the storyline as 'remember when that crazy guy posed as the late Victor Lord?' OLTL knew how to correct the situation, and that's what B&B is doing here in not giving credence to any of those stupid Y&R Sheila stories.