Tensei Arasaa Joshi no Isekaikatsu: Seiryaku Kekkon wa Iya na node, Zatsugaku Chishiki de Tanoshii Kaikaku Life wo Kekkou Shichaimasu

An ordinary woman in her 30s wakes up to find herself reincarnated as Magnolia (3 years old), the daughter of a prestigious marquis! What she thought would be a happy life in another world awaits her, but what awaits her is mistreatment from her family...and an unwanted political marriage!

(Source: Tonari no Young Jump, translated)