I started a series at least a year ago (2014-2016?), there were 2 books at the time and I cannot remember the titles, and I do not trust the character names I remember because a Google search turns up nothing. They are not at my library anymore because I looked at my checkout history and the entries had been deleted since the books are no longer there (lost or weeded, I guess because they were not old when I read them).
Here is what I remember:
Setting: city/state based on Italy, perhaps Venice, LOTS of Italian names of places/characters, but the author does not use true names he makes up his own (I'm pretty sure the author is male). There is a center city surrounded by islands where the merchant families (upper class) live. Palace is in the center and the city/state is ruled by a king who is supported by the merchant families.
Girl from a well-to-do family is set to be chosen for one of the 2 schools the class always attend. Her little brother is chosen, but not her. Her parents eventually end up trapped in the castle as a power-play by the son of the king who wants them to make him the king (he has to have the approval of the families in order to become king). She keeps the family's island/home safe by blowing the horn each evening (something her father does when he is there). She discovers magic within herself and saves the kingdom. (I remember even more details, but I do not want to bore anyone)
Different main character. This follows the story of a boy who is a slave. He believes that he has a curse because all of his masters die. He is working for a troop of actors and is actually happy, but then their ship is attacked by pirates, thus prolonging his idea of his curse. He ends up stranded on an island and, enlisting the help of other marooned people, makes his way to a city where he claims a ship the people of the city believe to be cursed (everyone who steps aboard goes mad, but he does not). They crew the ship and manage to make it back to the city with information of an attack. They meet up with the main character from Book 1 who helps them with her limited magic to thwart the attach, mostly with illusion magic. He eventually discovers that the ship is a special ship that should only be able to be used by people from a certain family, and that his mother is the missing daughter of this family.