Was the same for me too, it was a telephone appointment though. All they asked was a few past addresses and date of birth etc x
All they did with mine was verify the certificate in person, was a 5 minute in and out job x
I added another child but I’ve not heard anything back. On my journal it says something along the lines of child details verified and when I click it it says I don’t need to do anything further so idk if they’ve verified it with hmrc for child benefit or something
They just verify the birth certificate that’s it, you just go in and out, for me anyway