@cary Not exactly - what happens is that when on POS screen (or quotation, or sales order, etc), when you change the value of the price list, the price list rate in the children in the document get updated. If there is no entry in that price list, nothing changes.
If you insert all items into the document first. Next, set price list field to your top-level price list (master / list prices / etc). The price list rate will update to the rate set in that price list. Then, you change the price list field to your special price list. The only items that will have their prices updated are the ones with entries in the special price list, and the rest will be intact.
There is no cascading look-up or price list tree yet, but changing the price list in this manner updates the prices to reflect what you are trying to do until that feature is implemented.