To support the upper levels of your pour, probably the most common practice is to use longer stakes, driven downward through what will become finished area of the step below. As the concrete stiffens during the initial curing process, usually at the same time you do your final trowel finish, the intruding stakes are then removed & the holes are packed in with cement & troweled as you do your finish.
Anywhere you will have these stakes which need to be removed from inside the finished area, be sure you have them attached to your forms in a way they can be detached from the form without disturbing the form itself. One way to do this is to screw a block to the form, then screw the stake to the block. In this way you can unscrew the stake without needing to pry against the form. Except for the stakes inside the finished areas, the actual forms should remain in place for 16 - 24 hrs. before they can be (carefully) removed.