Kodomo no Mama demo Mama ni naritai! - Dokidoki★Happy Home

Three elementary school aged girls - Misaki, Saya, and Marika - suddenly arrive at your house. They come from different environments and have different personalities, but an AI has determined that they are extremely compatible with you as a family and it has decided to put you together to live under one roof. The three of them may seem like just young children, but they will heal you with their big love for you in a motherly way.

(Source: Kadokawa, translated)