Obviously, I adore Ambridge and Erwin as a couple!
If not for her attraction to Erwin, Ambridge would make a prettier heir. But I've already played Erwin as the founder of my Power of 10 dynasty.
Regarding NSS, what I've done is disable it completely for both "My Households" and "Other Households."
Besides the Have Babies setting, there's also an Adopt Babies setting.
I've noticed that if my sim does a "Discuss expanding the family" social with a friend, they might also adopt a nooboo or a pet if the spouse is already pregnant.
MarianT has the terrific idea of only enabling the Have Babies option (and Adopt Babies option?) in certain intervals, which is great for players not using MCCC.
Of course, turning NSS on and off whenever we wish is something we could not do for any of the forum's dynasty challenges except the BDD. *winks