Hi,
If I followed that, I’d say just try ditching the &displaystart command, and you could experiment with using [[UltimateParent]] instead of *parent* as the startId. (check the syntax on that, I’m going from memory).
Whenever different things are needed on different levels, more templates may be needed to house the different calls, or at least some way to pull in the different call code. I’ve had some clients that go crazy with different menus on every level. Wayfinder has never failed me, although sometimes it becomes really complicated.
Actually, for people who have ridiculously many levels, I usually suggest just doing a bare Wayfinder call, which shows everything in the menu in a sidebar, and just style the "current location" so they know where they are. They never go for this.

Well, I’ve just gotta charge more money!
Good luck, D