Hierarchical particle system for a forest

Question

I have two tree objects, each consisting of a trunk, and a particle system with leaves:

I would like to instance them as a forest on a mountain (a separate object). When adding a particle system there, none of the options seem to cover my use case:

1. When I select Render As > Object, and choose Ahorn tree, only the trunk (and not the child leafs.001 are rendered.
2. When I choose Collection and choose a collection that contains both trees, I get each object (two trunks, two leafs with particle systems, and leaves) separately.
3. When I choose Collection and choose a collection that contains only one tree, and then Whole collection:

I still don't see leaves, and the trunks are placed all over the place:

Is there an easy way to make a hierarchical particle system? I don't want to make leaf instances real, as this will crash blender due to resource usage. I suspect I'd see the same with the Particle Instance modifier.

I saw this question about a particle system for a forest, but it doesn't consider the problem of the tree using a particle system itself.

Answer 1

I managed to make it work with the use of geometry nodes, like this: