Organise: layers, positions, groups
Layers is the drawing structure your plan gets exported with.
Each layer has an eye to hide it and a count of what is on it. Add your own with + Add layer.
Positions is the naming your crew actually talks in — DS C 8, RW SL.
Add one with + Add position; the count shows how many fixtures sit there. Once fixtures have positions, Select position in the Edit menu picks a whole truss at once.
Groups are the third way to organise, and the loosest one.
Select fixtures and press Ctrl+G to make one; the same key takes it apart. The header tells you how much is selected. Click a group to select it again later. Groups arrive from two places and the panel does not distinguish them: you make them by hand, and an MVR import turns each hanging position into one.
A group asserts nothing physical, which is why it can span fixtures, truss and props without contradicting anything. Three other things in the editor look group-like and are not:
Coupled truss move together because they are bolted.
A fixture mounted on a truss moves with it because it hangs there.
A snapped assembly moves as one while snapping is armed.
Those are facts about the rig — attachment and topology — not membership.