Representing Different Floors on Parallel Backgrounds
A common practice, at least within my own company, is to represent different floors in parallel background drawings separated by an arbitrary and regular distance. It would be helpful for creating drawings if Design Master automatically added to these parallel drawings when a pipe would transfer from one floor to another. For example when a pipe from the first floor goes to the second floor in a vertical pipe it would be useful if Design Master showed the pipe going up on the first floor and coming up on the second floor automatically. These two entities would have to be paired so that deleting one would automatically delete the other to cut down on confusing and database problems (I think). This is especially helpful for multi-floor buildings with piping going from one floor to another quite often, like a hotel.
This feature already exists in DM Plumbing.
Michael Lenning commented
This you can already do with DM Plumbing.
Create the floors using the DM Plumbing->Building Definition->Floors command.
Insert an alignment point and an area around each floor plan on the drawing using the DM Plumbing->Alignment Point->Insert Alignment Point. You can do this all on a single drawing as you described. You can also have your areas on different drawings and it will work with no problems. It is helpful to define the pipe types that will be used in the area in this step.
Insert the pipe using the DM Plumbing->Pipes->Insert Riser command. Specify the pipe type and starting and ending floors. The pipe will be inserted spanning the floors. Moving or deleting it on one floor will more or delete it on the other floors.