As a Dad, bio and otherwise, I second what DrDeth said. The proper word is decided amongst the pertinent folks. The rest of the world can take a long walk off a short pier.
Well, I can’t imagine why the school would need to know if they are bio-siblings or adopted siblings. I don’t even know why the school would need to know if they are step siblings. But I also don’t understand why it matters to the parents.
Sometimes it might matter if the kids live in the same household (each household must sell a box of candy ) or if they go home together ( in my kids’ school, in bad weather the kids who went home together would all meet at the youngest one’s class and be dismissed together) but that sort of thing doesn’t depend on legally being any sort of sibling.
That was pretty much the point - the town was bending over backwards to make the non-traditional family feel uncomfortable. The gay couple were adults and resigned to dealing with such bullspit, but when the kids got dragged into it was a number of steps too far.
And this factoid makes the school board look even stupider than before. I agree with the point - (a) none of their business and (b) what difference does it make, who cares?
When a live-in boyfriend starts writing absence notes and signing permission slips for their partner’s child, does the school ask for proof of marriage or adoption? I never heard of such a thing - they just assume “responsible adult in loco parentis”. Why they would act differently for two adults who are actually married, boggles the mind.
Brings to mind the comment about faculty politics, which likely applies to HOA’s and school boards too. “Why is the politics so nasty? Because the stakes are so petty.”
i wouldn’t say the school asks for proof of marriage or adoption at the point where they get the permission slip , or really at any point. But they do ask for birth certificates and information about parents when children are enrolled and they don’t typically accept absence notes or permission slips from just anyone - at the very least, before the school lets the live-in boyfriend sign a permission slip or an absence note they are going to want written authorization from at least one legal parent/guardian. Which (depending on the time frame) both these women may be to both children - there’s typically a presumption that the spouse of the person who gives birth is the other parent and is listed on the birth certificate often regardless of gender.
“Who is allowed to write absence notes and sign permission slips with their own name” is a very different issue from “are these two children who live in the same household siblings”
But as far as the OP goes- I don’t understand why it matters. Let’s just say the guy isn’t the bio-father, isn’t the adoptive father and isn’t the step father. Maybe he and the mother aren’t married, Maybe he’s the mother’s brother who unofficially took his nephew in. In most circumstances, there is no need to distinguish one situation from the other and there’s nothing wrong with just using “father” just like most people say “sister” without going into details about how “she’s the biological sister I didn’t meet until I was 30” without a specific reason.