Blubelle my reaction would be much the same for anyone who was semi estranged from their family and then started using, not family names, but family dimunitives or nicknames in naming a child. It appears ingratiating, as if those involved thought it would curry favour.
They may have sought and received the Queen's consent. In which case that is fine.
I have nothing against them, except their public behaviour, which they must know will be commented on it. If you make a show of parading your noble and virtuous motivations in public. You must expect your behaviour to be judged by the standards you parade. So far I am not impressed.