For no headache to see the volumes falling in the infinite!

Make a volume(s) : group it (them) (alone or separated)
Faire un volume(s) : le(s) "grouper" séparément ou pas!
Copy an existing group don't work except if you group all the result of the copy + original!

Draw a Joint any where in the 3 D Space

All can be selected in any order
but always with Keys Shift &/or CTRL
Colors Bounding box is helping!

Here 2 groups separarated + only one Joint!