This might help, wrote it a while back. Launch it in the API window.
This macro will do the following:
1) ask you for a selection of elements you want to copy
Internally it will retrieve all nodes used by these elements
2) ask you for the original CSys
3) As you for the destination CSys (selection, i.e. there can be several)
For of each of these, it will
1)create copies of the nodes by replicating their coordinates in that new Csys
2) create copies of the elements by using these new nodes
NB: this was created for "simple" elements like 1D, 2D, 3D and rigids. I don't use SlideLines often for example, the macro may not be robust for these more "exotic" elements.
APav