So it just had the trinity symbols scattered all over it or a center medallion of just one? Never mind, I just re-read your original post. Definitely a medallion. It sounds like she just modified a Double Wedding Ring and figured out the intersections of the rings herself. Possibly it was just 3 large circles made up of slightly curved squares appliqued onto a sheet. No "melons" or curves to piece. That would be an easy pattern to draft on paper & would look smashing in a completed top with the right color placement to cause the "linking" of the rings.