That movie is set way in the future and the baby looks like both of the mothers. I don’t think it was an adoption, I think the assumption is that they somehow figured out a way to have 2 women have a baby together with both of their DNA in the future. I watched it with my kid n kinda thought huh, that’s a bit of an odd choice, but my kids didn’t ask, and frankly I didn’t care. The movie was shit though, and this tiny, weird bit of plot was irrelevant to it sucking. The decision to replace the voice actor for Buzz was super annoying. He just sounded wrong and the movie was fucking space groundhog day but worse.