Most of what i do is creating assemblies in context to a client supplied part Top down.

Sometimes i might wish to make use of some items i created in assembly 1 and use them in assembly 2 (under new names, and these items may well be in context to each other and/or the client part in assembly 1).

I might want to make minor changes to the items in assembly 2, but i DO NOT want those changes to be propagated to their original form in assembly 1.

I have tried pack and go to assembly 2's folder with new names, but im not sure this will allow me to modify them without changing their originals in assembly 1.

Is there a  process of doing this? im worried that the external references might cause issues between the 2 assemblies?