In literature, disclosure of donor conception in lesbian families has been considered an obvious and straightforward event. However, little is known about the ways in which donor conception is discussed in planned lesbian co-mother families. This study focuses on the process of parent–child communication about the donor conception on a within-family level. Six families, including 7 children and 12 parents, were interviewed about their family communication with regard to donor conception. A dyadic interview analysis revealed that family members managed the space taken up by the topic of donor conception in their daily conversations. Within these conversations, they also took care of each other and of their family relationships. In addition, children had an active position in the co-construction of the donor conception narrative. Linking these findings to the concepts of relational management and functionality of donor conception narratives, this study informs practitioners in the field of medically assisted reproduction.