BOM and Rev question

We have an issue with creating a part with multiple revisions.

When we want to add a revision to a part that has today's effective date, it automatically replaces all BOM that use that part to the latest revision. Why does it do this? I don't want that revision to be used on all other BOM's. I want to use it only on special revisions of certain parts.

What are my options?

Thanks,
Jasper


[Non-text portions of this message have been removed]