In Revit 2018 we are now able to have Multistory Stairs by Connecting Levels, and be able to unpin any of the upper levels stairs and change the Tead/Riser start number.
However, since we are not able to separate (ungroup) any of the staircase instances from the Multistory Group, in some cases we group the stairs and copy to the upper levels. In this scenario, there is a disadvantage: it doesn't seem possible to change the Tead/Riser start number of the group instances!