In both DAZ Studio and in Blender morphs are controlled with sliders, but those sliders don't behave in the same way. In DAZ Studio a slider can change another slider, but the latter can also be changed independently. Something similar does not really exist in Blender; either the slider is driven by something else, and in that case it cannot be changed at all from the viewport, or the slider is not driven and cannot be modified by another slider.
We can summarized the three steps above by the increments:
- Left increased 50%.
- Combined increased 50%.
- Left decreased 100%, right increased 50%.