Write a setup.cfg argument to install dependencies from other arguments

I'm writing a setup.cfg file for a Python package that requires different sets of dependencies depending on whether it's used for purpose A or purpose B (with some overlap). For development purposes, I want to add an argument to the setup.cfg file that installs both sets of dependencies simultaneously.

The relevant section of the setup.cfg file at the moment:

[options.extras_require]purpose1 =    pkg1    pkg2    pkg3    pkg4    pkg5purpose2 =    pkg1    pkg2    pkg6    pkg7    pkg8all =    pkg1    pkg2    pkg3    pkg4    pkg5    pkg6    pkg7    pkg8

The accompanying setup.py file is minimally dressed, and all our metadata is currently still kept in the setup.cfg file.

What the setup.py file looks like at the moment:

from __future__ import annotationsimport setuptoolsif __name__ == "__main__":    # Do not add any parameters here. Edit setup.cfg instead.    setuptools.setup()

So far, I've added the dependencies manually to the all argument, but this would require me to manually crawl through and add dependencies to the all argument every time the package's list of dependencies changes.

Is there a way to write the all argument such that it will install everything listed under purpose1 and purpose2 without the need for me to manually write them to all each time the environment changes?