???
Sorry, I read the link through several times. The decision of the court was that it still depends on the payor's blameworthyness in the situation. There was no black and white decision that the payor must inform payee of any change in income or automatically change support amounts.
The decision seems to me, and to the author of the report, to simply clarify aspects of "blameworthyness". It seems to me that the decision does tilt the scales of responsibility toward the payor, but it does not make it an unequivical responsibility to act automatically.
In my earlier post I made the suggestion that a payor may be spending more on the child while the child was in their care. In such a case, they may have a genuine feeling that they are providing the correct amount of support. This is one example scenario. The issue is whether there is any intent on the part of the payor to deceive or otherwise deny the proper support. Even an honest statement of "It never occured to me" would reduce or eliminate blameworthyness.
As such, the decision does not call for any automatic action on the part of the payor. It still lies with the payee to request updated information.
Current legislastion does not require parents to automatically forward updated financial information (ie tax assessments) yearly and the court has no power to alter legislation that specifically. Ultimately we still have to ask.