There is some catching up I need to do too in this respect. Note that what follows is only theory, I have never tried it. ;) One thing you can do is use a readScript line in each actor of the cr2 to load channels, e.g:

actor head
        {
        [other stuff here]
        channels
                {
                groups
                        {
                        [other stuff here]
                        }
readScript ":Runtime:libraries:!Injections:Conniekat8:MyFunnyFigure:MyFunnyFigureHeadChans.pz2"

                }
        }
[Next actor here]

The file referenced in the readScript "MyFigureHeadChans.pz2" Would contain all the channels for the head, e.g: { //MyFunnyFigureHeadChans.pz2

                targetGeom Morph-01
                        {
                        name -
                        hidden 1
                        }
                targetGeom Morph-02
                        {
                        name -
                        hidden 1
                        }
                targetGeom Morph-03
                        {
                        name -
                        hidden 1
                        }
}

You would need to do the same for each actor. The BODY is a special case, you would use valueParm channels in place of targetGeom channels. The point to this is that an update zip could contain a new version of "MyFigureHeadChans.pz2", that contained extra channels. The end user would need to answer the "replace this file" quire with "Yes" when prompted by Win Zip. The new channels would be included in the "MyFunnyFigure.cr2" at load time, when it read the readScript lines. The advantage being that you only need to distribute a new "MyFunnyFigureHeadChans.pz2" not a whole new cr2, and as far as I know it should work in any version of Poser. A down side is that this will only work on the original cr2, not on a copy that has been saved to a pallet from within Poser, because in such a file the readScript lines would have been replaced by the actual channels.

I will remind you that the above is just theory, and I have not tested it, though DAZ does seem to use something similar, with a few extra gimmicks.

My advice would be to include as many empty targetGeom channels as you think you may need in the original cr2, then add a few more "just in case", then add the readScript lines to each actor, just as a fall-back, in case you find you did not really add enough blank channels at some point in the future.

The other option, as nruddock suggested, is to use PMD injections. Personally I don't fully trust them. For more info on PMD see the tutorials a Nerd3D.

DAZ has something called "Extensible Parameters", unfortunately I have not been able to find any technical info on it, though is seems to relate to the readScript method mentioned above.