Here, let me clarify what I *think* will be happening.
The courtyard gates out front are where the line splits into 2 currently, right? I'm not talking about once you hit inside, I'm talking about the iron gates, the wait time, the test seat etc. Once you pass the iron gates outside, you have 2 lines. The one on the right, the bag line, the one on the left, the no-bag line. The new pathway will NOT be for lockers. It will simply be an extension of the LEFT hand side of the pathway leading into the castle. It will be there simply to hold more of the queue, without having it spill onto the main area.
Since the only room to expand the queue is this area, that means that the locker line (which currently is the right hand side) will be moving to the LEFT, and the no-bag line (which is currently on the left) will have to move to the RIGHT. Since this is opposite of where the lockers are placed in the castle, their will have to be an extra ride attendant once you reach inside (where the lockers are) to direct the flow of traffic, most likely to stop the non-bag guests and let in some guests with bags into the locker, then visa versa, stopping the bag guests into the locker area, and letting the non bag guests into the dungeon.
The new line won't go anywhere except down the side of the castle (maybe some zig zags here and there) and then back up, to go into the castle as the line currently does.