Massing Study with Multiple High-rise Buildings

I have a site with multiple buildings standing on different ground elevations.

I've made the buildings into separate families and put them together in a project file. However, since the buildings sits on difference elevations, I wan't able to find a way to create levels for all of the buildings. Is there a way to assign different set of levels for individual buildings? Thanks!

There is no sophisticated way to do this. The best way is to just create all the levels and use naming to distinguish what building they should go to. Levels not selected as Mass Floors for a particular mass won't cut that mass.