hmmm -- it almost seems like you'll have to create a different workflow, only because you have a Proposed model that is almost entirely different to the Existing model -- all because of the height change.
this is very much a work-around & has its own workflow.
TL;DR This'll be a combination of Hotlink Modulling & Renovation filters.
i'd approach the entire house the same way i approach multi-storey buildings. all your Existing & Demolition modelling work is done in the Hotlink stories & your Proposed model in the active stories. Hotlink stories are stories that are far above or far below your typical storey. we generally have them from -20 & below. Active Stories are basically your typical modelling stories. -- basement, ground & upper stories, etc.
say for example, i'd have your Hotlink storey at -20. put all your existing & demolition models in this -20 storey. assign the elements in their respective Renovation statuses (Existing / Demolition).
Export the entire storey as a module file (.MOD). make sure to make everything visible. don't use renovation filters that hide any elements just because they're Existing or Demolition. create 2 Hotlink Master Layers (one for Existing & another for Proposed).
Place one Hotlink Module in the Active Storey using the Existing Master Layer at storey 0.ground. This is your Existing model. Save the view with the Existing layer combo & Existing Renovation filters / Graphic Overrides.
Place another Hotlink Module in the same Active Storey now using the Proposed Master Layer at storey 0.ground + 2 feet. Save the view with the Proposed layer combo & Proposed Renovation filters / Graphic Overrides.
when you're ready to place new elements (doors/windows/walls/bathrooms etc) put them all in the respective Reno filter in the Active storey at the correct elevation (+2 feet).
When you're adding notes/documentation to the Existing / Demotion / Proposed views, put them all in the Active stories -- not in the Hotlink storey. FYI -- you'll technically be tagging different elements between the Existing & Proposed modules but they all come from the one source -- the Hotlink Storey. any change you need to make -- whether to add more stuff for Demolition, adjust it in the Hotlink Storey & see it reflected in both the Existing & Proposed models ready for tagging / adding Proposed elements.
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