This study examines descriptions of families after separation and re-partnering, with a focus on family boundaries between those considered family and those excluded from it. Adults in post-separation families may try to maintain a large number of family ties originating from various partnerships, or they may limit the recognition of their family to the members of their new household. Children, on the other hand, are encouraged to maintain contact with both parents and their relatives. Family descriptions of 48 re-partnered mothers residing in Switzerland, as well as their current partners and children, are analysed by focusing on exclusiveness and inclusiveness in written or drawn descriptions. Descriptions collected in family interviews follow a balance of social tensions among interdependent individuals by which responses of children usually match those of their mothers. Mothers’ responses show a high level of exclusiveness, whereas responses of mothers’ partners and children are more balanced between exclusivity and inclusivity. Inclusiveness in family after re-partnering is also connected to conditions such as family structure, mothers’ education, and employment.