Wave connection to SO Line

Hello! I am trying to understand the connection between a wave and the specific sales order lines that are on the wave. We have our system set to one wave per SO. When I'm on a wave, the Line Items tab includes the line # of the SO it's come from for each line. That and plenty of other evidence say that the data is there somewhere.

However, I cannot find a saved search path from wave (or pick task, or transaction) to SO line. I also cannot find a SQL path. I'd be happy with either.

My ultimate goal is a list of waves where any of the lines are already fulfilled. I can reach the sales order status overall, but I could have a partial fulfill situation, so I need to measure the SO lines directly. I can not match on item, because we often put the same item on multiple lines of the same SO for different reasons.