How do I have a material interact with its previous iteration.

So I am making a game where noises create spheres of sound that make an outline of whatever that noise sphere touches in a world of darkness. I am trying to figure out a way to allow 2 outlines on an object at the same time. I am currently creating a dynamic material and setting it as an overlay for the object.

Animation

(post deleted by author)

do you mind iterating more because the game i am doing has the spheres made my sounds that happen in the world and the player’s mic. I do not see how I can do animation to get this to work