Who do you think Abby's baby's father is? I think it would be best if she was already pregnant, but that boat has sailed. If it's Calian, the og Walker cast can be criticized for not being Native Americans. If it's Tom (after some redemption), we have some incest problems with Cordell, Abeline, Geri, Denise... If it's Hoyt, it would be weird to explain how we have a Hoyt that wasn't related to the Walkers. It could be a new character but I don't think it would be a good idea.
Good question! I'm going to go with Tom, but I should point out there are no incest issues with that. They've talked about Cordell being a fifth generation Walker. That means he's five generations removed from Abby, and therefore Tom. The closest way for the Davidsons and Walkers to be related is if Tom becomes a Walker, but has a brother that the current Davidson line comes from. Therefore, the current Davidsons and Walkers would have a shared sixth generation ancestor, making them fifth cousins. And since the US allows 2nd cousins to get married legally, there's no reason Geri and Cordell (or any other Davidson/Walker combination) couldn't work.