Background: This study assessed the feasibility and effect of two mobile modes (WhatsApp vs. a specially designed app) in their delivery of updates and assignments to parents.Methods: Two three-armed, randomized, controlled feasibility studies were conducted. Participants were randomly allocated to the control arm, youth-only arm, or youth & parental component arm. In the parental component, parents received updates and were requested to complete shared assignments with their children. In the first year, the assignments were sent through WhatsApp and in the following year via the specially designed smartphone application. Students and parents filled out questionnaires at three measure points: pre and post intervention and at three months follow-up. Mixed-methods assessments were performed using semi-structured interviews with parents and school staff members, as well as a computerized self-report questionnaire.Results: The addition of the concurrent parental component via WhatsApp was associated with superior improvement in self-esteem and identification of advertisement strategies, compared with the youth-only program. However, adolescents in the youth-only program delivered via the specially designed application demonstrated superior improvement compared to those in the youth & parental component arm.Conclusions: Although the addition of the concurrent parenting component was praised by the actively participating parents, overall, this intervention was not statistically superior to the youth-only arm. Only a few variables demonstrated statistically significant improvement, usually with a small effect size. The use of WhatsApp had higher feasibility and uptake than the use of the specially designed application. Under the chosen structure and population, it seems that the program did not have the intended impact. Parents who expressed specific resistance may have negatively affected their children, causing them to be less engaged. A cost-benefit analysis of programs with parental components as well as the development of strategies to enhance parent-school partnership are warranted.Trial registrations: NCT04129892 (1.11.2017) and NCT03540277 (26.4.2018)