Comment 3 for bug 171627

Originator: NO

This is impossible. Inkscape's groups use the same <g> tags as layers and
therefore they can't overlap. Besides, it would be ambiguous as to which
layer the group itself belongs, and therefore it would violate the
principle by which each group is an object that has all the same properties
as other objects. What you're looking for is named sets/stored selections,
filed under another RFE in this tracker.