Originally Posted by
ScienceTeacher
I’m lead to believe you cannot add someone to an existing booking that’s already ticketed.
That's true. There is no way to turn the booking for 4 into a booking for 5.
Since the booking has only just be made, it will still be within the 24 hour window for free cancellations and amendments, but as far as I'm aware (and corrections most welcome here) that doesn't solve the possible issue of availability. It would, from what I understand, still be a cancellation and rebook, with the risks that entails regarding the reward seats - it would just be at zero admin cost.
Originally Posted by
ScienceTeacher
You would need to cancel the existing booking with four of you on, hope the seats go back for sale, and then rebook.
The 12 year old can travel on a separate, linked booking. And as the OP is Gold, they will also be able to make a free seat request for them, as they have indicated they will be in the same cabin.
Whether that's a better or worse alternative than cancelling the whole thing and hoping the inventory reappears is for the OP to decide I suppose. There are obviously a few downsides to the approach of a separate booking, but there is the unquantifiable risk that the reward inventory doesn't reappear.....