Actually, no.
They did it before in the Legend of the Jade Phoenix. Joanna, Adian and Tel all separately demanded their Trial of Refusal, granted they fought it together, even Joanna who's own guilty verdict was at a reduced odds to the ratio Adian and Tel were guilty of, but she choose to fight with Adian.
This trilogy was written and set significantly before the Great refusal.
So no, they were not making it up as they went along in this case.
I'm sorry but how does that example support your point? If you're arguing that multiple trials of refusal can be fought over one verdict, well the fact that Joanna had separate odds suggests that each person had separate votes and that there was effectively three trials which were instead just lumped into one at the worst odds.
Which is a little different than one trial split into 8 different battles.
Plus we've already established that the IS as the aggrieved party can call for a separate trial of refusal. (Though why that separate trial wasn't at the odds of the original vote, or furthermore why it was the IS that determined the balance of forces is beyond me).
What exactly is the typical order for a Trial of Refusal?
The council makes a vote
dissenting voters can fight against the vote
aggrieved parties can fight against the vote
in both cases, the council determines the odds which are up to the ratio of the fight but are typically bidded down in favour of the defenders but still at substantially difficult odds (ie 16:1 becoming 4:1). The trial takes place in one fight.
Now with the Great Refusal what happens?
The council made a vote
the Aggrieved party disputes the vote
So instead of typical policy, the it instead becomes some sort of batchall thing. The council says what they're defending with. The IS then determines what they're attacking with. Then the battle is not one battle but 8 battles with the winner being that which won the most (and then of course contrary to various fluff, the fan-favourites predictably win their battles).
Is this a Trial of Refusal or a Trial of Possession? Why is the IS bidding? Why are there multiple battles? Why is the ratio of the original vote not at all factored into the equation? Aidan, Joanna and Tel didn't vote. But they still fought at 3 to 1 odds. They were the aggrieved party. Why would the IS be ANY different?