Yea, Bella is the easiest and most natural progression. The others require doing things that would be contrary to the "right" thing.
Just had a finish where I got mom and 3 sisters preggers. Had everyone living on the island and in the epilogue it says I also got Riley and Adriana preggers. Rebecca, Nia and her gf/wife preggers. Alina, Ana and Kira preggers, Sasha, Miley and Sabine preggers. Bella's friend Megan preggers. I'm surprised it didn't say I pegged James too lol