I think this is very likely a relative (ancestor?) of Edelgard and Lord Arundel. She has the Adrestian color scheme (Red, Crimson, Scarlet, and Gold), Edelgard and Lord Arundel's eye color and natural hair color, as well as a flower with Eagle feathers attached to it in her hair
(Going to replay here so then I can use images).
Hopes tends to try and use similar hair colour palettes in order to make it clear certain character are related.
As show by your examples:
Claude and Shahid
Hilda and Holst
Lorenz and Erwin
Linhardt and Waldermar
Caspar and Leopold
Ferdinand and Ludwig
Dimitri, Rufus and Lambert
So on.
The exception to this rule is Edelgard and Arundel which fits into the family history of the Hresvelg in the game. Since there are traits that makes them different.
Edelgard doesn't share her original hair colour with Arundel as her is a much light brown while Arundel a very dark brown. She also doesn't share eye brows design either. What she does share is eye colour with her uncle.
Meanwhile, similar to Edelgard, Ionius hair colour is white, identifying a connection between the two and imply that like Edelgard. Ionius has went through something that created his white hair and his sick health.
Since Edelgard hair wasn't originally white and she sorta has to get her lighter brown hair from somewhere. Edelgard hair design during the coronation is also similar to Ionius with it strands like nature. Both character also share the same eye brows as well.
However, the main difference between father and daughter are the eye colour.
So far Fortune Weave has done something similar, using hair to define characters sharing ancestry. But also specific character feature like facial design, eye brows, eyes design and clothing. It doesn't have to be all of these but it has to be one.
Under this understanding, when analysis the new female character alongside Edelgard and Arundel. There is no full similarities. The shade of brown is different, same with the eyes design and eye brows.
The colour is also a much dark purple rather then a lighter purple.
A character who is slight more similar to the new female character is Lorenz which is point out by a JP user:
Both character has similar eye brows design, more similar eye colour and design. Similar facial structure alongside hair design.
