Question about Miqo'te names (not conventions)

[Erendis]

I can't recall who referred to F'lhaminn without her clan letter,

Pretty sure it was Niellefresne.

Also in Y'shtola's last scene in 2.55 (when she cast Flow), didn't she say "Farewell, Mhitra", showing cracks in her stoic facade that her sister is obviously close to her in her heart? (I'm too lazy to check my screenshots to verify this ).

I've replayed this just last week and she does say "Forgive me, Mhitra", which I did not realise the first time since I did not know about Y'mhitra back then.