Ockham made Morph Mirror. I used to use it all the time. I'm not sure if it works in 9/2012 tho, but it worked great in Poser 8, although I'm am sure I was working with obj morphs and not those made by the morph brush. Worth a shot tho. ;). If it doesn't work, I suppose you could still work on one side of the figure, export an obj out, reimport and mirror. I guess. LOL.

Laurie