For posterity’s sake, I’m including a link to said now-locked weekly question thread.
I noticed that statement about six sisters, and I think it’s just a typo or ambiguity in the text that they are part of a set of six, i.e. the six includes the speaker. In a different echo for the Granary, the text makes explicit there’s six total. (There’s a remote possibility of a Captivating Princess situation, an additional sister born after the Second’s fall, but please don’t believe this.)
I believe there’s contradictory or incomplete information about which sister is which. I have the Attendants reset but not yet replayed, I will be examining it closely.
I stated last week that I thought the Roseate Queen is in one of the three tombs in Willson’s Monument. That was a misinterpretation of the Queen’s interaction with the first tomb, where “from behind the glass, she waves at her own tomb.” I have changed my mind, I don’t think the girl waving is the Queen as a child, but the Queen’s memory of her dead sister.
On the other hand, I do believe the second tomb contains the Obstinate Adoratrice, who you can meet in Parabola. Both sisters associate this tomb with the sun, of which the Adoratrice is the architect. I re-played her parabolan campaign, and the text implies she left her body behind.
I’m not sure who the third tomb belongs to. My best guess is the Mother Superior, who died only recently.