I tried the "Include Morphs when conforming" method by conforming one copy a figure to another one.

All face morphs of the conformed figure were "slaved" properly to the parent figure.

So as long as the new mask uses the same cr2 structure as the figure it is supposed to conform too, everything should be fine.

(Tested with M3RR where every face "morph" is actually a morph. - Newer figures have a lot of morph dials that aren't morphs, but ERC-controls of several morphs grouped together. But it "should" work the same if the cr2 is identical.)