I think the real question is about a method for actually handling a simultaneous collision of multiple circles.

Example: suppose 3 circles (1 circle with radius R & each of the other 2 circles with radius 2R, each circle with an arbitrary mass) are positioned so their centers are 4R away from each other & form an equilateral triangle. Suppose the circle with radius R begins moving at constant speed (from rest) towards the circumcenter of the equilateral triangle it had formed with the other 2 circles. Geometry & Physics guarantee the circle with radius R will collide simultaneously with the other 2 circles.

The question is, "how do we handle such a collision correctly - as experimentally verifiable - as possible & how do we scale to account for 1-to-n simultaneous particle collisions when n is greater than 2?"