Add Ons to Memberships

I was trying to let Police & fire be able to have 24/7 access to our facility no matter which membership type they bought at no additional charge. currently the only membership able to access 24/7 is the Gold membership. Having to set up so many different memberships for all the different nuances is very confusing for the members and looks like too much when you see them when you are trying to sign up. I saw the prerequisite button and thought I could do this but it doesn't work and I was told I could do this. Please reach out if you need further clarification.