But a study of Bolsa Familia in Brazil concluded that the urban poor - especially those who are highly mobile, such as migrants or those without a fixed address - can be just as 'hard to reach' with social protection as the geographically isolated rural poor (Wong et al. In some cities and towns, the poor are concentrated in specific areas. In others, the urban poor are dispersed throughout. Children are often sent to live with wealthier relatives, or left behind with grandparents in the village when their parents move to town to look for work. Mobility and splitting of households raises questions about who should be the recipient of social transfers. For instance, if a child is named as beneficiary of a child grant the recipient is usually the child's primary caregiver.