My issue with Ania being a distant cousin or descedant there is that the generational gap between Jag and Jaina(and Fel II) and Legacy is not that large. Just about eighty years and in Star Wars people have kids in their thirties and forties after all. As for Zekk/Taryn or Trista Zel I'm sure they have descedants and Zekk more than likely married the former but why would Ania have the solo name? That doesn't make any sense especially in a matriarchal society like Hapes A Jaina/Zekk shadow child's descedant is possible and I could see something like that happening(out of drunkenness or a moment of emotional vulnerability or maybe some sort of manipulation/alien influence) and they both agreeing to keep the issue hush hush and send the child away. Though the times involved are sketchy. The context of her backstory is obscure and cloudy and not indicative of her being royalty or having come from it at least recently(both in her profession her attidude and those around her's knowledge) so that makes more outlandish ideas a little more likely. As for Anakin and Tahiri-quite frankly I'd sooner believe Leia cheated in the LOTF era given the timeline constraints but it isn't impossible and I was just listing possibilities no matter how unlikely.