I was just lucky to spot this: the reason (or at least a reason) you're crashing is that Nikodemes isn't a legal greek_cities faction name - I think you meant Nikomedes.

I tried to do what you describe some time ago and failed. The show_err indicated (I don't remember the exact wording) that there could be only one male family member without a father (this would be the faction leader of course). This would rule out starting with a son-in-law. I tried this again today and got a different show_err saying it couldn't find the spouse, though she was definitely there.

I won't say this can't be done just because I haven't figured it out, but it isn't straightforward.