Delphine is the surrogate mother of her sisters.  In the absence of her mother, Delphine has operated as the maternal figure for her younger sisters. Being eleven, she is the eldest of the girls.  Delphine has felt responsible for them and does what a mother should do.  She is the guardian of the money.  She ensures that she and her sisters eat, even demanding for grocery money to buy food when their diet of Chinese takeout disagrees with them.  Delphine is the figure towards whom the sisters look towards when they are in trouble.  Delphine does not evade the relationship of responsibility she has with her sisters.  Rather, she seems to understand that in the absence of a steady and providing mother figure, Delphine has to assume this responsibility.  

At a critical moment in the story, Delphine tells her mother that she does not "up and leave."  This reflects the relationship that Delphine has with her children.  She does not "up and leave" and abandon them.  Delphine's relationship with her sisters binds her to them, ensuring that they are nurtured and cared for.  This embodies the hope that she has for herself.