Diphylleia’s Plan to Coup is a Manga/Manhwa/Manhua in english language, Manhwa series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Thao Vy--- an 18 year old girl in the spring of her youth, the precious daughter of a bread store owner on B???i Street. One night, while studying for her college entrance exam, after eating her mother’s homemade roasted chicken sandwich, she suddenly was transferred to another world?!

What do you mean by a new mom & dad? A new biological older sister? An older twin brother?! A ritual? A school for nobles?!

A ridiculous situation brought her into a state of sorrow, and from that moment onward, she will have to live in another body, live with another name; Diphylleia de Emboriel -- the youngest princess of the glorious Emboriel Empire.