Look, I've been banging on about this for years. This post (
https://www.greenandgoldrugby.com/schoolboy-rugby-a-modest-proposal/) is almost ten years old, yet nothing changes. But here goes again. The old school groupings are not fit for purpose. This is clearest in the GPS, where no fewer than three schools (TAS, High, Grammar) field their 1st XV in the 3rd XV competition. While Cranbrook and Trinity produce a good side once in a while, St Aloysius has not been competitive for some time, and the CAS competition is usually fought out between Knox, Barker and Waverley.
What's needed is a competition of (at least) three divisions. Rankings should be based primarily on the number of teams fielded, and the attitude of the school towards its Rugby program. Promotion and relegation should be possible if schools improve their programs or want to taper down. It would be healthier for everyone if Barker and Waverley slug it out with Joeys and Riverview in Division 1, while St Aloysius, St Andrews and Grammar play against appropriate opposition in Division 3. Obviously some schools could be unhappy about where they're graded initially, but over time things would sort themselves out. You could still have GPS, CAS, ISA teams... they'd just be picked from different divisions, but that's OK. In any case, the new pathways have rendered those schools representative games less significant than they once were.