Previously, you were not able to extend a booking if the Registration expired in the extended period.

A new system parameter has been added to the 'Booking Validation' parameters to allow the extension of a booking where a registration will expire. 

If this parameter is set to 'Yes' you are able to extend the booking if the Registration expires in the extended period. 

Note that this parameter is set to No by default so will have no bearing on your current process.