@Lexer615 I'm not sure what you mean by the relevant Arcs - but when I got the badge for having a mer baby it was my human sim with Salty Seaworth. they decided to build a house on Mermaid Secret Island when he showed it to her and they lived together there and she had a merbaby with him and it was the first baby. I've since moved their household into my Big Game and they've had a son who is also a mer baby.
FYI: The default scale colour at birth of girls is pink and boys is orange/yellow. You'll need to change it if you don't want them all looking the same. It gets a bit boring after a while. But they are nice colours when you first get them.
