Treatment and support of people diagnosed with severe mental illness in Sweden takes place in out-patient psychiatric services or municipality services. Most of the responsibility for support in daily life are provided by the close family. One crucial matter is how to support these families. This research project aimed to investigate the Swedish construction with shared responsibility between county psychiatric care and municipality social care for consumers with severe mental illness affects actions in municipalities in relation to family support. Ten representatives from five municipality settings were interviewed. Five semi-structured interviews were analysed using a thematic analysis. The following themes emerged; One overarching theme, "a mismatch of paradigms", and sub-themes: (a) "accentuating differences", (b) "doubts about including the entire family in the same session" and (c) "lack of a uniform family support policy". We conclude that a shared mandate needs a dialogue between psychiatric and municipality services concerning this mismatch.