If you don't mind some manual work - add a label to your map and click on it's properties. Then add the URL for the parent map. Name the label what you want and now it's a navigation object.
Gotta do what you gotta do - hope it's not too many maps?
If so have you looked at NPM 11.5? The world map now handles groups on the map - I switched to all Groups and no nodes - now everyone can click through the world map and just use the - or the zoom fully out button to go back up. 10/10 recommend