Where does default workshop trade dialog come from ?

[SKKmods]

I am trying to track down the default "Just Wanted to trade a few things > OK " player initiated talk for WorkshopNPCScript actors assigned to a workshop.

 

The player dialog options seems to originate in Quest.Followers.Misc.SharedInfo.PlayerSharedOpenInventory conditioned by GetIsID player.

The settler responses seem to be in Quest.WorkshopParent.Misc.SharedInfo.WorkshopParentSharedXXX conditioned WorkshopDialogeFaction.

The shared settler responses are re-used all over the place, but I cant find the actual trigger Info or Scene that kicks the player ask.