Leave the IC the same I say. Let tensions gradually rise from it. The natives will grow bolder with the weapons supplied by the PRK. Tin will respond with violence (that tends to be their go-to solution, doesn't it?) and maybe tensiona could rise from hordes of oppressed and starving fugitives trying to flee across the border to the elves' side.

Eventually Tin's investigation can reveal the PRK and lead to them either declaring war or perhaps trying to incite the Tinites inside the country to rebel. Alternatively Gustavo could come back, see that he didn't start a war, and do Willy's plan.

Edit: the reason I want tensions to slowly rise is so that Tin can be out of interregnum and actually fight a war, and because Willy seems to want a few posts of peace as well.