I just realized something. Those Hearth-Kin, way back when, at the moment of the Congerie when they all got unexpected sex changes… how did that work? Wouldn't a lot of them have used Becoming to undo that? The Congerie happened after the wars in the interregnum started to die down, so presumably enough time had passed for them to work out becoming in at least one magical tradition.
Questions this line of thought brings to mind:
Was there a splinter group that rejected the change?
Did the Congerie metaphysically prevent them from returning to their original sex? Did it have psychological side effects that made them okay with this?