thank you all for taking the time to reply.
I assumed as well this wouldn't be a big issue since the two lap infants are the same people, just with different legal names.

I did call the gold line, they seemed a bit confused and said that name changes are not permitted but that they would go over the documentation and make a decision, though she could not guarantee at that time that it would be possible.

I'm keeping the booking, I feel confident they will allow the name changes.