Originally Posted by Biri
But even if they new, there was still Albert and his heirs, before Leopold and Lilian's children.
Leopold's children were excluded from succession, it was stated when they married.
But if Albert had no children, Baudouin would have been lacking an heir. Until 1991, only male line descendents of Leopold I could inherit. And besides him and his brother, there were none. The succession allowed in absence of an heir for a king to name one with parliament approval. Perhaps Leopold could hope that Baudouin would choose one of his half-siblings. It seems more likely he would have IMO chosen one of his sister's children. Prince Jean or Guillaume may have been likely choices, or even one of the girls, introducing absolute primogeniture and applying it to earlier generations instead of simply Albert's kids.
But I find it hard to believe anyone could know Fabiola couldn't carry back then. Even with the advancement in medicine today, it isn't always easy to tell. Trouble conceiving is different then carrying. In a virgin of those times, it would have been extremely hard to know.