Transfer registrants

We have a case where the organisation wishes tickets that have been purchased to an event being transferrable. So for example if a registrant becomes sick on the day of the event they can authorise a transfer to someone who has not yet registered. I was wondering if this is something that would be handy in the backend, to be able to transfer from one user to another user, thereby fixing up any issues like correcting the invoices, tracking number of registrants for the event and accurately showing the user's history of attendance etc  
Is this something others have wanted or requested?

How about editing the registration record and update registrant data to the new user? What's the problem with that approach ?

Tuan

Tuans way I use quite some times.

I can imagine your approach to be handy but they need to be joomla users and all the input fields like address and so on need to be replaced.