If you shorten the stem by cutting the mesh you will alter the number vertices and cause Poser not to accept it. If you move the chair and stem up and down in the base without moving the base, it will work. Make the seat and stem one part and the base another. Put the two parts together, scale it how you want the final to be(in zero position) and export. Move the seat up and export, move the seat down and export. Bring the zero position version into poser with all boxes unchecked and add the other two exports as the morphs. -JH.