How to have one "master" subscription plan, encompass multiple other subscription plans


I have set up the membership pluggin and have multiple subscription plans working just fine.

The flow goes as such...

Member joins as free member, then has option to pay for additional subscriptions based on what content they would like access to.

Right now I have all content open to the visitor and the "download" link protected by the appropriate subscription plan/access level short code.

My question is, say a member joins and would like to join all the subscription plans at once, currently they have to submit payment and "join" each one individually.

How do I set the "master" subscription to automatically "enroll" the member into all the other subscription/access levels at once?