Often times many music festivals will have a set of temporary outdoor stages erected as performance spaces. Currently the only way to denote a stage being festival-specific is via a disambiguation, and even this does not always readily convey that the Place is only erected certain times of the year.
Examples of this relationship:
Summerfest has festival stage Miller Lite Oasis
Miller Lite Oasis is a festival stage for Summerfest

I should add that it would be a good idea to enable the normal begin and end dates fields for this. Occasionally festival stages get dropped or their names change (and there's little way to accurately keep track of it all).