A recent query one of my clients had, was on how to add an opening to a staircase landing. The default Revit opening commands cannot cut through a staircase, whether it is a run or a landing. An in-place void also does not cut through a stair (I avoid in-place families like the plague anyway).
As can be seen from the images below, we need incorporate the tree into our staircase design. The green circle represents the opening we need to add to our stair.
Edit the stair and modify the landing boundary to incorporate half of the opening required.
Mirror the landing on the horizontal boundary line to create a complete opening through which the tree can pass.
Delete all unnecessary stringers and railings. You will notice that we still see lines indicating that this stair is actually composed out of two landings. Using the linework tool, we can override unnecessary lines using the Invisible Line linestyle.
The final result will look as per the image below