Despite the growing body of literature on how migrancy transforms family relations, surprisingly little research exists on how ‘migrant family’ takes shape in institutional encounters. In this article, we analyse the negotiations on when and how family relations become addressed in encounters between social workers and migrant service users. Drawing from institutional ethnography, we understand the local service encounters as actively regulated by extra-local relations of ruling, represented here mainly by texts such as legislative acts, service descriptions and professional guidelines. The results show that the ways in which family is present and addressed in the institutional encounters often became an act of balancing between a broader understanding of family relations building on the service user’s self-definition as well as psychosocial and holistic professional ideals, and a narrower administrative understanding rooted in the Finnish legislation on social security and immigration. The legislative texts thus become a strong relation of ruling that coordinates the actual encounters and what happens in them. Nevertheless, family is essential to human subjectivity, and if the institutional encounters focus only on those family relations recognised by the legislation, important aspects of human relations remain unseen.