I Usually sellect the nodes I want to copy. In Windows, I can hold down the shift key, and left mouse click all of the things I want to copy. Then I go to the node where I want to change the nodes. Again, I can hold down the shift key, sellect the things I want to delete, and delete everything at the same time. Then a paste, and reconnecting loose nodes finishes up the job.

I also copy nodes that I want to preserve to the Preview window so that I can undo my changes later on, if I decide to.

LMK

Probably edited for spelling, grammer, punctuation, or typos.