Scouse is already aware of the stuff I dug up about the Dukes. I'll post it here for anyone curious:
Datamined stuff about Duke Stelmane (who we know is important, due to the mind flayer connections): Most of this stuff takes place in Act 1b in Moonrise Towers "The Cult of the Absolute has ransacked the inn at Waukeen's Rest and kidnapped Duke Stelmane of Baldur's Gate. The player arrives after the carnage, finding corpses strewn about. The player casts 'Speak with Dead' on one of these corpses...
Quote
"a civilian that was caught in the middle. She stopped in Wakeen's Rest with her husband and daughter in the middle of their journey to Waterdeep for a wedding. She watched her family butchered by goblins before being killed herself."
"one of the drow raiders. He was killed by a Flaming Fist archer perched atop the inn."
"a member of the Flaming Fist who was sworn to protect the Duke. She was among the final Fists left standing. She was killed guarding the Duke."
"one of the goblin raiders. He was killed chasing a child through the inn."
"A group of Flaming Fists are trying to force a way into the burning inn at Waukeen's Rest. They can hear someone inside - they believe it might be Duke Stelmane, who they had been sent to protect. They recognise Wyll, and insist that he helps"
What the player can know: "TavernInvestigation_Knows_AskedStelmanedescription" "Player knows Stelmane is on the top level of Moonrise Towers" "Player knows Duke Stelmane was kidnapped"
"Councilor Florrick is working in secret for a dragon in the city of Baldur's Gate. She is acting as an advisor to Grand Duke Ravengard. She should come across as good but no nonsense. She is used to getting her way."
"Ravengard's counsellor is trapped within a burning building. The Flaming Fist is one of several that forces their way inside. She calls to them when they enter, and the FF yells back to her."
"A group of Flaming Fists are trying to force a way into the burning inn at Waukeen's Rest. They can hear someone inside - they believe it might be Grand Duke Ravengard, who they had been sent to protect." <- interesting how one instance it is Ravenguard, next it is Stelmane. Perhaps things got switched?
An ox "refers to Duke Ravengard"
Nothing on Duke Portyr. I assume Thalamra Vanthampur is dead after the events of DiA, nothing for her either.