The trick was to set 'data-active-class' value with the 'data magellan' attribute. This then tracks ands sets a temporary '.is-active' class against the magellan targets. It is quite clever because it holds the 'is-active' class on until the next target is reached. This means that the target remains highlighted in the navigation even if you have inserted more sections (at the same level).
Then a little css in the header section to change the navigation link (when it is '.is-active') and you have tracking navigation. Magellan also sets smooth scroll in all directions!
Enjoy.....
Cat herder and Fog platter.