You can increase radius to get rid of overlapping objects. There will be empty areas that You might fill with smaller objects.
Sometimes this can work. more info in [ur=https://forum.itoosoft.com/forest-pro-(*)/crystals-population-(or-any-other-custom-objects)/msg12645/#msg12645l]this thread[/url]
Unfortunately ForestPack does not have other collisions evaluation method like mesh or convex hull.