This circles back to the theory that Morrigan's mum was a Wundersmith.
I read a pretty recent post about how Squall freaked out about Morrigan singing his personal song in order to summon Wunder. And that made me think, either it was related to his power, or he snapped for emotional reasons. Since this is Squall, I think it's the latter.
What if Morrigan's mother was the Nevermoor equivalent to being Force sensitive? She wasn't a Wundersmith exactly, but she had a small connection to Wunder and a small connection to Squall.
I feel like this is also a Snape/Lily situation. Squall (Snape) was in love with Morrigan's mother (Lily) and now has a small hatred for Morrigan (Harry) due to his jealousy of Corvus (James) but still wants to protect Morrigan.
Maybe the song about the little crowling is about Morrigan. I'm assuming Morrigan's mother died shortly after giving birth, so maybe Squall grieved so much that he re-invented his Nocturne song in tribute to Morrigan, and Morrigan's mother.
But then again, this very well could connect to the power possibility. What does happen if a Wundersmith sings another Wundersmith's song? Does it sap their power or something like that?
But then again, what if Squall is actually Morrigan's father? No, Jessica Townsend wouldn't do that. That's too cliché, right? . . . right?