In Dreams of Ice, when Moenbryda is introduced, we see this exchange.
Yda: Moen! Gods, it's been ages!
Moenbryda: Oh, longer, sister!
Y'shtola: A joyous reunion indeed.
Yda: Well, of course it is! Moen and I are like twin sisters!
Papalymo: ...Save in appearance and aptitude.
We now know that Yda, while being the same woman we have been acquainted with throughout Final Fantasy XIV, is actually Lyse, and her older sister is the former archon Yda. So, this leads me to ask some questions.
1) Are Lyse and Moenbryda both 'in' on her secret here, and they are both genuine old friends, presumably from while Lyse was in Sharlayan, where Moenbryda was?
2) Is Moenbryda *not* in on Lyse's secret, and yet they somehow spent time to become close friends--"like twin sisters"--sometime in the past six years or so since Lyse has taken up her sister's identity?
3) Is Moenbryda *not* in on Lyse's secret, and Lyse is simply lying through her teeth about being Moenbryda's friend, perhaps coached by Papalymo beforehand, having learned that Moenbryda and Yda were old friends?
4) Was it 3 or 4 seconds of thought that S-E's lore team gave to the coherence of their own story before green-lighting a "Yda is Lyse" twist purely for the sake of expansion hype?
What say you, Lore Onemind?