Body groups, that is that tab under the Node tab?
Currently it is working now, with setting things on different collision layers (just remembered that from the GDQuest 2D tutorial). So now I have 4 physics layers: "Cars", "Track", "Environmental Hazards" and "Triggers" and all of them only have the "Cars" layer as a mask. Don't know if this is the right/optimal way of doing it? It seems to work though.
I imported the track, assets and animation using Blender, exporting it as a glTF, with the NLA animations. The 4 rocks that fall, are also different nodes/objects, as you can see in the image. Or is that not what you meant?
Problem is, that they need to play at exactly the same time. Atleast that is how I animated them in Blender. So for example, if rock 1 starts falling at frame 1, rock 2 starts falling at frame 8, rock 3 at frame 11, ... .
