The nobles would not be able to contradict this since Blanca was here as the Master of the Magic Tower's fiance.
This was exactly why Blanca was introduced as Alwin's guest at first. And now his fiance.
Blanca would not have a hard time in noble society with the power that the fiance of the Master of the Magic Tower holds.
If they had just introduced Blanca as someone they met for the first time in Safiro, the noble households would never agree to her becoming one of Arabella's maids.
Formerly, the nobles feared sending a maid to the palace but now, they must have already begun their preparations when they heard that Renee died. They likely quickly thought of who would possibly replace her.
And thus, they would have prepared someone from their family to be sent if there was a selection just like Arabella did when she hired her assistants.