12. The Birth of Ganesha's Daughter - Goddess Santoshi

Goddess Manasa (popularly known as Mansa Devi) was Lord Ganesha's sister.

Lord Ganesha was married to Riddhi and Siddhi who were created by Lord Brahma. He has two son - Shubha and Labha from them respectively.

It is said once on the auspicious day of Raksha Bandhan, Goddess Manasa visited Lord Ganesha for tying knot of Rakhi as per the festival traditions. 

When Ganesha's sons, Shubha and Labha saw the love and bonding of brother and sister between their father and his sister, they desired to have a sister.

Lord Ganesha granted the wish of his sons, and created a feminine form from the flames of holy fire. She was named Goddess Santoshi. Goddess Santoshi gained her form from Riddhi and Siddhi who were Lord Ganesha's consorts.

Goddess Santoshi is regarded as the Goddess of happiness and satisfaction. Here is a short story regarding the birth of Goddess Santoshi.
(Note - The word Santoshi literally means satisfaction)