action button on Case create

Hi

SugarCRM Enterprise v25:

On our Cases module we could like to put an Action Button on the 'Case Create' view that assigned the Contact is unknown to 'Master anonymous' contact record. I can do this on the cases that have already been created but that is of no use. What i want to do for colleagues is to put the button on the Case create screen so they don't have to look up this contact (or inadvertently create a new one) 

Is this able to be done?

Kind regards John