Many factions already have Vvardenfell hooks planned for them, but while the Twin Lamps and East Empire Company are not directly joinable in vanilla, they are/will be joinable in TR. It might be a good idea to let players on Vvardenfell know about this by giving J'Zhirr/Canunctian Ponius some dialogue about the offices in Old Ebonheart and Firewatch, like: "I'm sorry, but if you're looking to join the East Empire Company, you should go to Old Ebonheart or Firewatch. We're already fully staffed at this office." and that when Grasping Fortune releases, Ilmeni Dren gets some dialogue for "business" that's something like: "There's no more business for you here, but if you want to help further our cause, you should talk to [Person] in Narsis. That's where we have the most influence."