How was the king king anyway? I didn't want him to just inherit from his father, but I absolutely have to have some legitimacy to his rule. The heroine doesn't much care, being seven and chiefly having noticed he was a bad man, but once in the story, it is clearly important. All the more in that people will notice and compare to her, given the magical way she picked it up.
And it had to be legitimate because he could control the magic associated with the monarch, though not so well as the heroine. She is closer in relationship to the founder whom it was centered on. I was thinking they were both collateral relationships (everyone's related to that founder, just some further than others). Both descendants I think would lead to their having to have too similar control; he can't be that many more generations away. Then, she might be descended and him collateral. Or maybe I say being descended from those who control the spell helps but may have ramifications for how the magic works that would throw off the plot.
And I have to decide whether it's the Queen who must give the first age-appropriate hospitality, or the families of other children can invite her. It would probably be best to start with the queen.