You could also remove gc item from menu and build simple automation to add the gift certificate order for you and check the ask admin pin option for the automation command. This enables the ability for other users to add a gift certifcate with the admins permission.
Or even just hide the button non admin users.
I have been thinking about giving free gift certifcates also.
The problem I see with this, in terms of accounting is that because you have not tendered any money for the GC, your sales report will be incorrect.
I plan to create a separate gift voucher, which will apply the payment as a discount.
I have the voucher generating, I just need to work out how to constrain a user overdrawing their credit using calculation types.
Am i right in my thinking on this. For example if you have a voucher (or a gift certificate that has not been paid for) for €5 off something it should be thought of as a discount and reduce ticket total, not the remaining balance as it does now.