Hi @spikeyxxx,
I tried with the instace modifier and could not get it to work. I suppose there is something wrong with the workflow I chose.
So using the sapling tree I create a tree base and add within the plugin leafs (based on a own leaf design)
The leafs are parented to the tree

When I select the tree in the particle system, it’s only taking into account the trunk and not the child leafs

using the instance modifier gets me the same results.
When I try to join both leafs and treetrunk, it not only joins the leaf object to the trunk, but mixes it with the instancer:

So I guess my question is, is there a way to achieve this with two objects that are parented to each other, or do you need to work using nested particle systems -> particle system of leafs to tree trunk and a second particle system of the tree trunk to the ground plane?