Ma Santoshi is daughter of Lord Ganesha. Ganesha has two wives Ridhi and Sidhi and two sons Shubh and Labh.
On the day of Rakshabandhan when Mansa Devi tied Rakhi to her brother Ganesha , then Shubh and Labh asked their Mothers about Rakhi and the festival. Both the sons Subh and Labh asked their father to give them a sister who will tie them rakhi.
Subh labh asked their father to give them a sister as they also want to celebrate Rakhi.
Ganesha decided to give them sister and he from his powers gave them their wish, Santoshi Ma .
Santoshi mata tied rakhi to her brothers Subh and Labh.
Santoshi ma is the goddess of Satisfaction .