Quote - But with that approach you wouldn't be able to add the morphs to an existing character, only the default cr2, right?

Yes, that's right. Only the default cr2 is affected by the update. Strictly speaking it is not the cr2 that gets updated, it's a some pz2 files. The default cr2 has 'readScript' lines which 'call' the pz2 files. However when you save the default figure back to the library from the Poser interface, those readScript lines have been been replace by the actual channels that were read in from the 'called' pz2 files. A copy (saved from Poser) of the original figure has all the channels from all the previous updates, but does not itself get affected by any subsequent updates, the reason it does not get updated is because it does not contain any of the readScript lines.

You could edit the readScript back into any cr2, and it would then get updated like the original, but that's not something the average end user would want to do. Perhaps a Python script could be written to add the necessary readScript to the cr2, but Python  is not my field.