In this paper I establish that there are a number of family forms where there are at least two mothers and challenge the assumed legitimacy of the dominant ‘one mother’ discourse. Research on open adoption relationships (Greenwood, 2011; 2012) suggests that naming of the two mothers is particularly difficult for all concerned. The difficulty in naming points to the problem which is that of the unitary signifier. To have more than one maternal subject carrying the name ‘mother’ in relation to a specific child disrupts the dominant discourse of family; the bedrock of our society.