Sample size calculation and randomization
We calculated the sample size for each group separately as the outcomes differed. In a previous study, the proportion of breastfeeding women that stayed in care was 41% in Kilimanjaro [The proportion of children reaching 95% adherence was 72% in a study among orphans in Dar es Salaam [The proportion of adolescents reaching 95% was 67% in a study among adolescents in the Kilimanjaro region [Randomization will be done using stratified block randomization on the strata of inclusion site and sex. We will use computer-generated random numbers, which were then programmed in the randomization module of the redcap. Those who enrol participants or assign the interventions only press a button in the database after entering the inclusion site and sex of the screened participant to give them the randomisation outcome and, therefore, cannot predict the allocation.