When Marco and Star arrive they are told to ask an old wise lady who lives in the mountain.
There they find a tribal placement with nobody but what seems to be an old woman who looks exactly like Princess Dih (even the clothing and color pattern are almost the same)
After being revealed that's Meteora in disguise it is explained the old lady did exist, but sadly died along with the other members of the tribe, leaving Meteora as the only remaining magical warrior to protect their territory.
And here's the thing, Meteora claims that old lady found them and raised them as her daughters, chosing Meteora as inheritor of her magic spells.
Not only that, everything Meteora knows about magic is because of her (which seems to include Butterfly mode)
Finally, there's the warrior mask: a wolf's skull
Remember Dih's dream was to run away from the castle and start a new life with the boy she loved, which she described as becoming lone wolves in the wild.
What if she accomplished it by running away to the Neverzone? After all, her sister despised her for being Glossaryck's favourite.
The tribal pattern + wolf masks + knowledge of Butterfly magic... that was totally Festivia's daughter.