It seems like the intended quest route from beginning to end is (General Act 3 quest spoilers):
Mess around in Rivington and have Orin make herself known to the party -> Gatekeeper into Wyrmrock + Ironhand Gnomes -> Raphael makes his offer -> Coronation -> Learn Duke Ravengard is in danger -> Learn Florrick is in danger -> Baldur's Mouth -> Emperor's Hideout -> Stop the Murder Spree -> Sorcerous Sundries -> Infiltrate the Factory -> Long Rest (Elminster + Mizora) -> Gale -> Gondian Prison -> Factory Part 2 -> Hostile Wyrmrock + Save Florrick -> Long Rest + Ravengard tells about Ansur -> Defeat Gortash -> House of Hope Information -> Long Rest -> Balduran Trials -> House of Hope -> Astarion -> Long Rest -> Thieves Guild -> Bank -> Minsc -> Zhentarim Fight -> Murder Tribunal -> Orin (Requires Murder Tribunal) -> Finale
Orin feels more intended as the final of the Chosen because the entrance to the endgame is literally right outside the area before her fight. Unfortunately there isn't really a good place to slot Shadowheart in as the house of sorrow is in a part of town that you are really only going to go if you are being thorough, but if you are being thorough then you probably end up doing things all over the place. Ethel also isn't really on the main path because you don't really have a reason to go to the Ironfist office unless you ended up in prison. Also I don't know if Orin actually manages to kidnap any party member if you never see the scene of her doing so (though iirc it triggers if you exit the Emperor's Hideout into the sewers) and she'll default to the girl instead and her timer (like 3 long rests) doesn't start until after the Murder Tribunal. afaik
