Derived Parts question

Looking for best solution for a situation Like this:

Example of a process of a part from square raw material:

- op 10 - rough top

- op 20 - rough bottom

- op 30 - finish top

- op 40 - finish bottom

Each operation has a model that is derived from previous op. simple and easy.

Here is my question, if i have for example ten similar parts but different sizing, how can i "copy" those 4 files so they still derived to each other but has different internal ID number?

I was trying "save as" each op and then import previous op from new part number but this is too much work on complicated parts and too much to explain other people how to dimension things to make that easier.

My second though was to do "pack and go" which seems work great but i'm not sure if internal ID change during this process. I someone can confirm this it would be great.

Any other options?

SolidworksParts And Features