For what it's worth, contacting just Marche is a bad idea. Telrunya isn't super-uber active OOCly, and, even ICly, neither D'Hara's prime minister, nor even D'Hara's House of Lords, will be making the decision of what to do about Port Nebel alone. Dunno how it is in Barca, but I communicate more with the Elders of the Véinsørmoot than I do with the realm council of Terran.
Maybe if Coli wants to do some political pressure, he should realize that, if there's fighting over Port Nebel, it'd be, in very large part, Terran's army that he's fighting? Because I'll say that, as far as any IC information my character has, the situation looks very clear cut and simple: Amaury seized Port Nebel and is holding it hostage. No other contact has been made by Lurians, and there are no moderates among them. That's how it ICly looks for most of us in the Véinsørmoot.
Full Disclosure: I'm trying to OOC hint to you to negotiate with the Véinsørmoot on the whole, because of my OOC (and IC I guess) goal of making the Véinsørmoot a very strong organization, and this type of conflict can easily cement it together.