Nic said:
All I can suggest is that you sit down with your Mum & Dad over a cup of tea and ask them how THEY would like to celebrate their 50th.
And you said:
I am thinking that it may be worth while paying for my parents to have a romantic dinner somewhere nice just the two of them on their anniversay and then hold an informal family gathering at the weekend.
These are the two thoughts I would go with. to you nugget, it's not an easy situation. x