Combine Audience Library and Activity Only Audiences together

Description

Ability to Combine Audience Library audiences with activity-only audiences and attributes

Why is this feature important to you

We have default audiences that we use to help gate campaigns to their proper areas. Because these are part of the audience library, we have an explosion of 1 off audiences

How would you like the feature to work

When Combining Audiences for an activity, it would we great to be able to select from the audience library, activity-only library or create a new container with custom attribute and combine them all together.

Current Behaviour

You can combine audiences from the library OR create an activity-only audience customized by Target attributes