Issue looping through all placed foliage trees using world partition

I am currently trying to build a blueprint which loops through all placed trees using foliage paint to get the positions of them.
In case of using a normal Landscape without world partition I can easy do this with this:

In case of using world partition I just get the trees from 1 cell.
What do I need to do to get over all placed trees?

I hope someone can help me with this.