Piddingtons's views found more favour with Marie Stopes, an English activist, and shared her opinion that motherhood could exist independently of sex and marriage. A summary of her lectures was issued as "Tell Them! or the Second Stage of Mothercraft" (1926), following her earlier pamphlet entitled "The Unmarried Mother and Her Child" (1923). In 1916 she had published her adaptation of the ideas founded in eugenics, perhaps in response to the 1912 conference in London, "Via Nuova; or Science and Maternity", a story or parable of a woman left without a suitable partner by the gender imbalance of young men lost in war. The central character is moved by religious and national fervour and becomes a single mother with the 'aid of science', a scarcely veiled depiction of her own progressive ideas. Her novel was published under the pseudonym 'Lois'. Working as a publicist, Piddington sought to associate herself with nominally allied groups and agencies in pursuit of her causes, but shifted allegiance when the objectives contradicted her own views. She was a founding member of the Racial Hygiene Association (RHC) of New South Wales in 1926, and through them gave lectures on sexual education, but disassociated herself when their objectives turned against her promotion of public education on sex, procreation and unconventional parenting. A rival organisation was formed by her in reaction to the RHC lobbying for the ban of Stope's book "Contraception", which she succeeded in having lifted. Marion Piddington's contribution to the history of the eugenics movements was international, but overlooked in the studies of the British and American organisations. She became well known in her lifetime for promotion of social causes, but overshadowed by the works of her husband in the courts and parliament during politically turbulent periods. Her own positions and character presented difficulties to later researchers, mixing sexual emancipation with the objectives of the eugenic movements, and the first major study of her life was not presented until the 1988 entry in the "Australian Dictionary of Biography".