Have Arvedui's sons already escaped to the Grey Havens? If not, this might be a good time for them to do so.
Just some ideas, take them for what they're worth (not much
)
but perhaps after the Emissarys are rebuffed with Arvedui, they might go to his sons to plead their case. I don't believe it says anywhere in Tolkien's writings
why the princes of the north abandoned the king. It would be a fairly large bifurcation of the story, and I don't know if you want to do it, but perhaps some of us dissatisfied Elves and Men ought to head south with the princes, and get on the ship Cirdan will provide.
Again, feel free to slap me down if I'm out of place.
On another note, I deleted my save 'cause I want that post to go after Arvedui's reaction instead of before.