Stair Numbering

[Anonymous]

I am trying to work out how the stair numbering can continue onto the upper surface which the stair joins, but is a different material to the stair.

eg. i have a level change of 450mm
i want to insert 2 steps 150mm each, and use the upper floor to be the top riser.
i can get archicad to number the steps 1 and 2, but can't find a way to automatically add number 3.

I have attached an image. the stair on the right is what i am after.

I apologise in advance if this has been covered in this forum, but i can't find what i am after!