Custom pkg(1) Manifest Question?

I've built a custom perl distribution pkg(1) that installs under /apps/perl5

There are other applications that also share that filesystem but none of them are pkgs.

The pkg(1) installs fine but when I try to uninstall the pkg(1) it tries to remove the entire /apps filesystem presumably because it thinks it's the only pkg(1) using /apps.

What is the correct way to setup the pkg(1) manifest so that it doesn't try to remove the /apps base directory / filesystem?

I've included the first few lines of the pkg manifest for reference below.

# pkg name and version info.

set name=pkg.fmri value=pkg://site/perl-gnts@5.12.5,5.11-1