Stop "Spawn Sound 2D" from a different blueprint?

I’ve seen all the posts from this thread:…-2d-sound.html

However, I’m unsure of how references to other blueprints work with Spawn Sound 2D. Is there a certain variable that is created by “Spawn Sound 2D” that can be referenced in a different variable?

I’m trying to make music fade out after the “Start Game” button is pressed. However, as the Title Menu is a Widget, I do not have access to the Timeline blueprint.

If I can accomplish this in the widget without referencing a different blueprint, I’d love to know. However, I’d also like to know how one could reference Spawn Sound 2D from another blueprint or if manipulation of currently-playing audio can be accomplished using a blueprint other than Spawn Sound 2D.