Bake foliage into level LOD with simplygon

I’m using Unreal Engine 4.19 with the simplygon plugin, creating a tiled level and trying to get the foliage to get baked into level LODs

So, if I place all my trees and plants as a static mesh, one by one, and then I go to the levels screen, and try to generate LODs for my tiles, my trees and all the other static meshes will become part of the lower LODs that EU (with Simplygon) produces.
This doesn’t seem to happen with objects placed as foliage (whether with Foliage painting tool, or procedural foliage spawner).

Is there any way to actually do that? Can I get my foliage to become part of the lower LODs for my tiles?