Como Vastra e Jenny se conheceram?

De acordo com o link

Vastra is a female Silurian warrior from prehistoric Earth who was awakened from hibernation in the 19th century when her lair was disturbed during the construction of the London Underground. Initially enraged, and after slaughtering five commuters, she was pacified by the Doctor and eventually overcame her race's hatred of humans to become a part of London society and a consulting detective to Scotland Yard and a possible inspiration for the Sherlock Holmes stories.

Jenny's backstory shows she was turned away from her family because of her "preferences in companionship", and saved from attackers by Vastra, who took her on as an employee. The Doctor was present at their initial meeting, during which he saved Jenny's life. She shows herself to have acquired extremely formidable skills as a hand-to-hand combatant and a swordswoman. She has also become familiarized with future concepts involving technology.

Não há fontes para isso, mas suponho que isso seja reunido a partir da exposição fornecida nos episódios. O link contém entradas semelhantes.

1. Vastra e Jenny não são "praticamente amantes" , são casadas.
2. A reunião deles não foi exibida na tela. Não tenho certeza se foi em forma de livro, ou se será.

Estou certo de que eles são casados e Vastra regressou no tempo, onde conheceu Jenny. A única coisa que eu não sei é quando e isso está me enlouquecendo porque eu revisei cada episódio e ele não diz quando.