I started a Ghost/Shadow/Mostly Flesh and Steel/Clean Hands playthrough. In "High Overseer Campbell", I completely avoided Granny Rags because I didn't know her tasks could be completed without locking these achievements...
Later I found out that it is possible, and that I need to complete at least one of Granny Rags' and Slackjaw's tasks to unlock their area in "The Flooded District" - and I need that for the "Art Dealer" achievement.
I replayed "High Overseer Campbell", hoping that GR&SJ's area in "The Flooded District" would be unlocked if I did Granny's tasks and completed the mission - but it wasn't! (I did both of Sj's tasks in "House of Pleasure" on the 1st try btw.)
Is there a way to change my previous choices in my playthrough that's already at "The Flooded District"?