helen wrote: It would certainly make selections easier if there was a junior ranking system
Agree totally with Mharky here, with the added rider from an ex-selector's viewpoint that it would actually make life far more difficult (Why wasn't my child selected when s/he's ranked Xth?), especially as orienteering seems to always want a ranking scheme that compares wildly disparate events and treat them all the same.
I hate ranking schemes, or at least all those that have been used in orienteering - they are highly artificial constructs which try and do something that simply can't be done. What matters in orienteering is what you do in the forest on the day that matters, not what I did versus what X did on a different day in a different forest.
Far better than rankings: individual leagues based on a few well selected races, and on people racing against each other. To that extent, the only ranking that ever made any sense to me was one used back in around 1975, when the top few in each class were ranked based on how they did in the JK, British and Regional Championships. Not pisspottical regional/badge events.