Ok, now it's easier to follow you.
Content Center files are generated on the hard drive where the content center family tells to. Those parts are REAL content center, and editing options can follow ONLY 2 strategies. If you "save as custom" you generate a new geometry based on the content center, and you are free to edit this new geometry the way you want. I will name this second one a "less REAL" content center part.
How to change REAL Content Center parts
We have 2 strategies at our disposal.
1. change one or more table values in the family table. This will affect only members that are using this parameters. If you change the value of your member "Executive 120cm QR", when you load an assembly containing THAT specific executive and do the workflow I have suggested a couple of posts ago, you will see what I have described (for example if you change a value to 121 cm)
2. replace the family template. This will affect all members of your family, as normally it is not a parameter
Be aware that this applies in a first instance to those parts which are REAL Content Center parts
Now how to get the "family template"? This can be obtained exactly with "save as custom". Once a specific geometry is saved as custom it can be used as family template for propagating the change to your entire family. So once you have done all your changes, you can right click the family, chose "replace family template", pick the file that you have just edited, and the changes you have done to that file will propagate to all members.
How to change "less REAL" Content Center parts
In case of parts that have been "saved as custom", changes to the family table will still affect the corresponding parameters that are linked in the part. Depending on what you want to obtain you need to consider how to edit that "saved as custom part" (changing geometries, un-linking parameters...), but I suspect that this situation is still quite far away from yours.
I still do not know enough of your specific system, but I suspect that this is what you need is to "replace the family template". Be aware of what you are doing, contact me if you feel uncomfortable by doing it 😉
Massimo Frison
CAD R&D // PDM Admin · Hekuma GmbH