This article presents the results of research that documents the role of a sperm donor known to the lesbian parent families serviced. The overall objective is to analyse how the various players (the biological mother, the social mother, and the donor) stress and express their ways of envisaging parenthood, kinship and fatherhood in a context where more than two adults are required for the reproduction and education of a child. To carry out this analysis, 9 lesbian couples and the 9 donors to their parental projects were interviewed. The results have shown that the sperm donor acted as the middleman in the creation of parental links, thanks to the mothers having structured an “ontological choreography” (Thompson, 2005). These choreographies work in synergy according to the predominance that the mothers give to the daily structuring of their family, to the distancing or integration of the social discourses as regards the importance of the father’s involvement for the child’s development, along with the creation (or non-creation) of the donor’s paternal identity. Finally, it is this that will determine the role of the donor with the children born of his donations.