Revit :: Concrete Step In Slab Annotation

I've had a request from on of our users to replicate something that has been done for years in 2D CAD. They want a marker to show changes in floor levels that look something like this:-

The annotation needs to be able to read the slab on either side of the step marker and hopefully if possible the difference be represented as text. The datum levels are secondary and it is really the depth of the step that seems to be more important. I do however want to avoid these being just dumb text as if/when the design evolves someone will forget to modify the text.
 
Here is an example of a few showing two steps in the slab and the results we would want.

I have tried loading/nesting a standard spot level in thinking if I had two in an annotation that this might work, but I was unable to even place a spot marker within the family which makes some sense I suppose.
 
Is this even technically possible...? I realize the origin usually determines what hosts the family and how, but I guess we are looking for something with a double origin, which is why I think this may not be possible...?