I am making a decision tree for a healthcare cost-effectiveness model. I would like to display a small circle at the intersection of edges, to illustrate that these branches are "chance/event nodes". I also want to be able to do the same with a small square to indicate a "decision node". (Quotes on these because node means something slightly different than in yEd-- I'm talking about the point at which multiple options split off).
In my example, I have a node "Eligible for testing" that then has edges going to "offered testing" and "not offered testing". I want there to be a small black circle right on top of the T where the edges split coming out of "Eligible for testing".