did you know you can copy a control, select another, and paste to replace? Would you like to do the same thing with sub VIs and constant on the block diagram? Then this shortcut is for you:
ctrl-shift-v to copy the path of a selected sub VI / typedef.
ctrl-v to paste-replace over a selected sub VI / constant
It does work by storing the path of a vi / typedef on the clipboard, so the source has to be a saved sub VI or typedef. It also means you can copy the path from a text document, and paste-replace from there.
There you can copy a object (not just a VI but a primative node) with CTRL + C, then use the replace command in quick drop (CTRL + P) to replace an object. He also has an insert that works on the same concept.