Is it possible to have a Private flag on a version to make it private to that project only, and not visible in the filters or comboboxes for the parent project?

We find that cloned issues moved to a subproject (forked code branches) lose their "Product Version" value when we update them because the parent project's version doesn't exist in the subproject. We figure we can create a "(main branch)" version in the subproject to signify issues found before the fork (and we can follow the relationship to the original issue to find the true version it was found in), but then this special version appears in the filters for the parent project.