That sounds like a different situation, if the OP is able to book their mother into the QG cabin, she will be able to dine in QG.
@e&mcruise I have no idea how this would work but a Travel Agent or Cunard direct should be able to advise.
It's good to hear that you want to return to Cunard after your first experience.
Your question seems to have caused a discussion about travel insurance, I'm not sure that's what you had in mind. What do you want to know ?
As far as I know the party unable to travel will be marked as a No show but there will be no refund from Cunard. The other party can travel as a single occupant of the booked cabin.
(This is not from personal experience just from my reading of these boards)
It's being reported on a Live from on the Viking board that one of their ships is still docked in Cape Town so Queen Victoria is still waiting for her parking spot.