So the MC's an idiot. Is she planning to go live on the street as a toddler? She might be "ignored" by her familly, but she's got a roof, food, clothes, caring maids, access to a library, etc... The fact she's the only one who doesn't understand there must be a hidden reason and, despite hearing her father and grandfather arguing about "going to such length to hide her from the royal family" in front of her, doesn't ponder this new information and proceed with her plan, doesn't reflect favorably on her intelect.
Her "gotcha move" is just cutting her nose to spite her face.