LG VX-8100

Is there a way on the E815 to change the speed dial number of a contact (call him "Contact A") to another speed dial number without completely deleting the contact who presently has the speed dial number you want to switch to ("Contact B")? What I'd like to do is to change the speed dial number of Contact B to another speed dial number, but not delete Contact B. Do I have to first find who has the speed dial number I want to switch Contact A to (Contact B) and switch Contact B's speed dial number before switching Contact A's speed dial number? How do I find the contacts listed by speed dial number?

Thanks in advance.