Hide other packages on listing form

Hi
I have two packages for event listings but only want one to show on the listing form on the frontend. The other one is for my personal listings that I add on the backend.
I have the ‘frontend’ package set as default package. I tried selecting ‘admin only edit’ on the package in the custom fields and this does hide the packages on the listing form however when I click ‘submit listing’ I get an error message saying ‘Save failed due to invalid package! Cheating huh?
How do I ‘hide’ the other packages?
Thanks in advance!