If I understand correctly, you are after a very standard menu output where the current page shows the children and also shows the siblings of all its parent hierarchy.
Unfortunately the standard menu output doesn't format the html correctly. It nests lists within lists which is fine for a menu but not for my use.
I need children and parents to be separate from grandparents and great uncles.
So I've resorted to asset listings which is working great for the grandparents in one list and the parents and siblings in another but it's not working for grandparents and great uncles ( confusing!!)
I could think of a couple of hacky ways around this, but they are probably not worth it in terms of processing cost. Can you just use JS to tweak the HTML slightly to the closest output possible you can get with just asset listings of the menu design area?