for Someone Else's Shoes by Ellen Wittlinger
Twelve-year-old Izzy, a budding stand-up comic, is already miserable about her father's new marriage and the new baby on the way. Then ten-year-old cousin Oliver and his father, Uncle Henderson, move in with Izzy and her mom because Oliver's mother committed suicide only a few months ago. And to make matters worse, Ben, the rebellious 16-year-old son of Izzy's mother's boyfriend, winds up staying with them, too.
But when Uncle Henderson--who has been struggling with depression after his wife's suicide--disappears, Ben, Izzy, and Oliver set aside their differences and hatch a plan to find him. As the threesome travels in search of Henderson, they find a surrogate family in each other.