From Maid to Mother

Description from Regina Books: (http://www.regina-books.com/lineup/detail/1043471/1775/)

Lily, a former school girl who is incarnated in a different world. Although I feel a little lonely when I remember the previous life, I am now acting as a maid who will be sent to the houses here and there, receiving the life of King Otoko. One day a sudden request came from Leonard, the royal palace wizard. Anything, he says he wants him to become “mother role” of Jill. Lily confronted Jill immediately decided to give her a 6 year old girl who is healthy and tameful! It was decided to live and work in the residence of Leonard, but a lot of troubles also occurred around him with wizards -?

From Mangaupdates:

A high school girl reincarnates in another world as Lily. While she occasionally reminisces about her past life, she is now known as “the Maid of the Royal Family,” after helping to rear the lady who eventually married the crown prince. One day, the court magician Leonard suddenly requests that she acts as a mother for his adopted daughter Jill.