That is also fair. I decided to rewatch the introduction song again to see if you were right but all it says is that Luisa and Isabela are older. It may be sort of implied that they’re twins? I don’t know that’s just a personal head canon.

Not at all my favorite Disney movie but it’s fun so long as we don’t think about those tiny details. I’m sure Lin Manuel Miranda wasn’t thinking about them that much since he renamed an entire character for one song.