Make children dammit!

[Paltmull]

So I'm trying to roleplay as Casse, not adopting or marrying anyone into the family. My faction leader, Barae, has two sons. The thing is, they don't get any children. One of the sons has a daughter, but that's it. I don't use them in the field or anything. They've both been governing cities for years. One of the two sons has a -1 fertility trait, but the other doesn't. It would be quite a pain to lose my campaign because of my stupid FM's bedroom problems. (sorry 'bout that one)

So, my question is: Is there any good way to aquire fertility traits/ancillaries for your FM:s? I can cheat if that's possible.