The Fertility Stone and the three Diana Cavendish

Through the history lesbian witches always existed, but they had a big problem, which was their need to keep their bloodline, but without being donated laying with a man or by adoption, since they need a biological child, but how? How did they will surpass the biology and have a kid with both traces of the mothers...
Simply The Fertility Stone
Created by the first Diana Cavendish of the Cavendish family it was the invention that become possible to lesbian couples form a fully biological family.
First Diana Cavendish? Three Diana Cavendish?
What?
There was three Diana Cavendish through the centuries before the anime one, the name of the actual Diana was based on them and how did this name become something very legendary through the history.
Wanna find out?
Give a read.
This is going to be a majority OC character story since nobody was alive at the 17th, 18th, early 20th Centuries.