the only reason i can think of is because she’s a dragon
I've come across a few where the younger sister either prover she would be better at it, so the other siblings supported her and a few where the siblings were never that interested in taking over or were the biggest fans of their sister and went along with what their dad chose. guess we'll eventually find out what the deal is here.
It's because she's a dragon. Dragons were the foundation of their family and they have a debt to repay to dragons. Especially when the species has been extinct for a millenia(?). That's what I think.
No he did it because the lilac family was trying to adopt her and this is the way he can keep her safe in the family
This is one of the think that i dislike on this kind of story how could it be fair for the father to make his daughter the head instead of her capable brothers ?