Hi.
Guess you are referring to tiled clones.
It doesn't necessarily needs tiling, you can create clones by pressing Alt+D once an object is selected.
Which parent object can be anything.
This case, if it was a group of even a single object, it could seed up your process.
Select "C", press Ctrl+G for the grouping, and clone the group (Alt+D).
Then, if you want to change "C" completely to look like "D", select "D", copy it (Ctrl+C),
enter the group of "C" (Ctrl+Enter or by double clicking it), select all (Ctrl+A),
delete (Del), and paste object (Ctrl+V).