Raise hell for this. She's endangering children.

I don't know your kids' exact circumstances, what their life was like before foster care, etc.

Your children have a biological father that they may recognize enough to say "That's my dad", and may not be in a position to say "he lost custody and is no longer allowed to take us".

Even if your kids don't? Other kids at that school might.

I've known adopted kids who had really complicated emotions and would choose to go with an unfit, abusive, dangerous parent in that situation. That's literally why we have those lists, because kids can't always be trusted to say "yeah that person is safe".

Kids get kidnapped by their relatives. Most kidnappings are committed by relatives, and it is CRAZY FUCKING COMMON to kidnap a kid from school when they use this "Yeah that's my dad"/"Yeah that's my grandma" instead of an official list of approved adults.

If the only thing she had said was "I don't know that you're an approved adult because I haven't seen you before and I don't have my list"? Fine.

But "you don't look the same and I already met their mother"? Fuuuuck no.