Making a staircase should automatically open up the horizontal planes above it. A bit like a window piercing a wall. Perhaps use the existing minimum volume to make it “perforating”, or have a 3D operation automatically generated...
I recently learned that it is possible to do this with ‘Connect/Create a hole with selection’. But it is not automatic. You have to make the staircase safety space visible, select it and then connect it... Whereas in most cases, a staircase pierces a slab above.
You could add the option in the staircase properties with a checkbox labelled ‘perforate the upper and/or lower slab’.
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