I would generally avoid exposing children to the Dom/Sub thing.
Not because it's morally wrong, but because it's fetishizing the initiation of force, which would really fuck up a kid's perspective if someone's trying to raise them without violence.
"Say Billy, you know how we don't hurt one another and that's real important? I'd like you to meet mummy and daddy's friends Spikytitsling Whipsalot and Nutcracker McTakesthepeg, they beat on each other for fun and then fuck."
Again, not making rules for human behavior here, just thinking about who I'd hang with if I had kids around.
"Mummy and daddy are all about the NAP but hang out with people who beat on each other for fun." Is a far more complicated topic to have to explain than the 'rubbing peepees together' conversation.