the easiest way is the following:
1. Patch your fixtures straight away.
2. Patch some Grouping Fixtures (grandMA3 library), you want to use as "parents" for some fixtures in the tree.
3. Select the fixtures you want to put in the tree.
4. Press Cut button at the bottom of the patch window.
5. Unfold the Grouping Fixture and set the focus in the tree below (see attached picture).
6. Press Paste to insert the fixtures directly below that Grouping Fixture.
ok thank you.