Foliage tool overlaps in single paint mode with multiple types selected

I want to paint trees on an ortho/satelite image using 3 different versions of the tree to get variety. When I have my 3 versions selected in the foliage type section and paint using the individual paint mode it places all 3 tree with each click. I would like to have it randomly place just 1 of the 3 trees with each click.

I have found a few other posts on the forums for this but none have answers. Is there a way to achieve this?

Other forum post:

Many thanks!
Greg