Combine 2 Content Areas - choose from existing content

Hey there, i have some experience with listing pages and perch itself but i don't know how to approach the following:

I have a) Events and b) Acts

A lot of Events are featuring the same Act-Lineup. So i want to archieve that my client can choose multiple already existing Acts while setting up an Event....

For Example:

Event 1 showing: Act 1, Act 2, Act 3, Act 4, Act 5 Event 2 showing: Act 3, Act 4, Act 5, Act 6 Event 3 showing: Act 1, Act 2, Act 3, Act 4, Act 5, Act 6

Any hints? Thanks in advance