Middletown by Sarah Moon
From Levine Querido:
Thirteen-year-old Eli likes baggy clothes, baseball caps, and one girl in particular. Her seventeen-year-old sister Anna is more traditionally feminine; she loves boys and staying out late. They are sisters, and they are also the only family each can count on. Their dad has long been out of the picture, and their mom lives at the mercy of her next drink. When their mom lands herself in enforced rehab, Anna and Eli are left to fend for themselves. With no legal guardian to keep them out of foster care, they take matters into their own hands: Anna masquerades as Aunt Lisa, and together she and Eli hoard whatever money they can find. But their plans begin to unravel as quickly as they were made, and they are always way too close to getting caught.
Eli and Anna have each gotten used to telling lies as a means of survival, but as they navigate a world without their mother, they must learn how to accept help, and let other people in.