Setting: mid-1950s England.
I would just like some feedback on the likelihood of this scenario before I begin writing, and some recommendations for sources I should look to for research.
Jane and Harriet are a lesbian couple in their late thirties/early forties, living together in England during the 1950s. Jane and Harriet do not look particularly similar, so they are pretending to be cousins. Between them, they have two biological children (Jane's ten-year-old daughter Rachel and Harriet's seven-year-old son Alan), both of whom were fathered by a gay male friend, Terry. (This results in some awkwardness, since the children both take after Terry in looks and resemble each other to a remarkable degree, considering that they're supposed to be second cousins rather than half-brother and sister.) Terry is in a sham marriage to Jane, so both Jane and Rachel have Terry's last name of Spencer. Harriet claims to be a widow (if needed, I suppose I could age Alan up or scale the story back so that she could claim her husband died in WW2). Terry does not live with Jane, Harriet and the children full-time (he is mostly "away on business") but puts in enough appearances so that the neighbours do not get suspicious. He sends a little money for the children (mostly in the form of material gifts such as toys, much to practical Harriet's chagrin), but the women have most of the financial responsibility for Rachel and Alan. Many years beforehand, Jane was married to a man and had two small children. When her relationship with a female neighbour was discovered, she was not allowed contact with her toddler son and baby daughter (Rachel's half-brother and half-sister) after the divorce.
I have read gay parenting books which advise against asking children to remain closeted about having gay parents, since young children have little concept of what is a secret and what isn't. How might Jane and Harriet discourage their children from telling others the truth about their family? I think it would be good to use the threat of being taken away or having the family split up (however, I don't want her to actually tell Rachel about her half-siblings, for fear of frightening her, and because it is still a very painful subject for Jane). How might the threat of being taken away from a tense but otherwise loving family impact on prepubescent children?
I realise this is very complex, so I don't expect anyone to tackle absolutely everything I've said here, but any insight is appreciated. As far as research goes, I've read The Queer Parent's Primer by Stephanie A. Brill and It's Not Unusual: A History of Lesbian and Gay Britain in the 20th Century by Alkarim Jivani. I've also entered various combinations of the words lesbian gay mothers parents history 1950s england into Google (it came up with reviews of a documentary called Mom's Apple Pie, about lesbian mothers fighting for custody after Stonewall).