We conducted a 12-week comparative field trial with 20 low socioeconomic status (SES) caregivers from 10 families to explore their use of a sociotechnical mobile application designed to promote healthy snacking, Snack Buddy. Our analysis of the semi-structured interviews, pre/post-intervention instruments, and photo-elicitation interviews suggests that participants gained a greater awareness of their own snacking practices and those of their family members. Users were empowered to adjust their own practices and beliefs around healthy eating because they were more aware of their family's snacking behaviors. We describe the unique social dynamics of how families engaged with each other and the application, which includes positive social support for healthy eating. By providing insights into family interactions and experiences with the application, we identify benefits, challenges, and strategies when designing family-level sociotechnical interventions for healthy behavior.