When adding an existing subscriber to an additional plan it would be useful if the subscribers details (address, telephone etc) could be used to fill the fields for the new subscription. This would apply to both front-end and back-end.
Cancel this request - the subscribers fields are filled if the current user is selected before clicking the 'New' button.
I was clicking 'New' and then selecting the user from the User drop down in which case the fields are not filled.