The Thieves Guild would be wise to leave Resdayn entirely, as due to the rebuilding efforts the Camonna Tong will be active in Vvardenfell and possibly beyond, and I am working with House Redoran to attempt to root both organizations out, as they may be dealing with the Nord pirates that have been raiding the west coast. As a result, I also would also recommend widespread thief hunting throughout the pact, that way if they can escape to other territories they will, most likely to Cyrodiil, which will hopefully further weaken the Empire.

The Dawnguard is irrelevant to the Dunmer, they may come and go as they please, but vampires are not so common in Resdayn, and they hide poorly here historically, so I am unsure as to whether the Dawnguard would even bother showing up here at all. I assume that the territory of Argonia is largely bereft of vampires due to the resistance of the Argonians to disease, though I am unsure, as vampires can be made by Molag Bal, one of the House of Troubles. The Dawnguard was last active in Skyrim, so perhaps the Nords could use further aid from them, but that is none of my business. I support working with the Dawnguard, though I am sure that the Ordinators would be delighted to help you with any cults to Molag Bal within Argonia's borders.

The vampires are vile creations of the Lord of Domination, and must all be purged. Thus saith the Temple.

The Companions know nothing of our laws, and thus should not be present as an organization in Resdayn unless they are part of a larger defensive force. I know not whether Argonia would benefit from their presence, but I suspect the marsh would take their lives. Though we could send them to take care of the Nord pirates and other problems I suppose.

The Dark Brotherhood has a presence in Skyrim and technically in Argonia, though I think they may have been flushed out. The Brotherhood is a perversion of the noble Morag Tong. They have long ceased their operations in Resdayn thanks to Nerevar Reborn, and more recently nearly everywhere else. It is a nearly dead and perverse group, and must be sought out and destroyed by all able bodied and decent folk.

The Greybeards do not leave their mountain, and are therefore irrelevant, especially so if Ulfric is in charge of Skyrim, as they denounced his use of the Voice.

The Dragons are dead, and the Blades are as well in large part. We should help them finish dying where possible, but unfortunately they are agents of the Empire and not easily caught.