When a path is selected, and the Extrude generator is selected, while holding the [Alt]-key, c4d makes the selected path a child of the Extrude - this is fast and very convenient.
It would be even more effective, when this also works when multiple paths are selected. And preferably, c4d should bring up a selector to wether:
-put multiple paths in 1 Extrude generator (and switch on 'Hierarchical')
-put every path in it's own Extrude generator.
Wouldn't that be great!