I'm sorry to see that the SP3 update did not fix this problem.

I never thought SIV3.6 would have ANY features better than the latest and greatest SI would.
I have resorted to dropping in an item (with accessories), then duplicating just the accessories (so they are distinct line items), then deleting the accessories attached to the main item. A little more labor intensive, but it works.
The only down side is that if I need to delete the parent item in a Change Order, I have to remember to delete the appropriate accessories.