Theoretical characters for the rest of the alphabet, assuming the game was gonna use all 26 letters.
J, K, L: 3rd handyman house, mother and 2 daughters, just to be different to the mother/daughter combo of the 1st 2 houses.
M, N: 4th handyman house, a pair of sisters. One works at the gym.
O, P, Q, R: teachers for the 4 classes.
S: a 3rd workplace. Possibly where Dawn or Ivy work. Other one of the sisters works here, too. S is exclusive to this job.
T: school principle.
U: a library exclusive character, like how Gwen is office exclusive.
V, W: workers in the mall. Older of house 3's daughters could work here, too.
X, Y: the coach of the swimming team and another member of the team.
Z: your older half sister. Since your father was married and had an affair with your mother, he could have already had kids with his wife. Sis found out about the 18 years of payments made to your mother, discovered what it was, and tracked you down to meet her long lost lil bro.