You can do it inside Poser. Set the dials of your face the way you want them. Go to Object/Spawn Morph Target. Name it what you want the dial to read. You'll find a new dial with your face morph. You'll have to set the dials you used to create it back to 0 (You can delete them if you don't need them) Set your newly created dial to 1 and voila! There's your combined morph!