I am building a large assembly of a few hundreds of assemblies/sub-assemblies and individual solid parts. I am using SolidWorks 2018. Some of my sub-assemblies are very similar. For example, in one of those, I have 3 individual solid parts. After I mate them together, I would like to create a new sub-assembly, by just changing one of those individual solid parts. I tried to do it and saving by: "save a new copy", but the problem is that the already existing instances of the old assembly automatically update to this "new" design. How can I prevent auto-update to occur, in the cases where I save the assembly with a new filename?