Why does Casey move in with her grandma?

At the opening of the novel, Casey lives in San Francisco with her father, Barney. Barney is hospitalized at the opening of the novel after being mugged outside the bookie's after winning a large sum of money on a horse racing bet. Because of Barney's hospitalization, Casey is first sent to live with her Uncle Phil in the wealthy part of town, and then with her grandmother, Paw-Paw in Chinatown. While living with Uncle Phil, Casey feels worthless, since her uncle and his family are only concerned with money and appearances; they do not allow Casey to live independently or have her own opinion on anything. When she proves to be too much of a hassle for Uncle Phil, who worries that Casey is a bad influence on his daughters, Annette and Pam-Pam, he arranges for Casey to move in with his mother in Chinatown.