My DH has a very English but unusual surname, and I have a non-English surname which I never contemplated changing. When DC were born, we gave them all his surname, but they all have my surname on their birth certificates as a middle name (so, think, "Tomkinson, Anna Paulette Jourdain" - not the real name, but like that).
My DD2 announced today that it's very "old-fashioned" that they should all have DH's surname rather than mine. I said it had never really occurred to me to do it differently! She thinks at least one of them should have my surname "to make it fair" and because "it's not very good for women's equality to just ignore your surname, you know?"
Further to this, she informed me this evening that she has "done research" and apparently Harriet Harman's daughter has her surname, while her two sons have her husband's. This, apparently, proves that it is normal. However, she accepts that daddy might feel a bit upset if she and DD1 both take my surname, so she's happy to be the only one with mine!
I actually knew about Harriet Harman's children, but I've never come across anyone personally who mixed up surnames for their kids. In principal, I think it is totally reasonable! In practicality, would it not be really confusing?
YABU - it's weird and confusing
YANBU - it's a nice idea and who cares if it's confusing?
DD2 is 9. I have no idea how she knows who Harriet Harman is.