Adding Outbuildings--Error messages

If first added in the parcel sketch, then add any future outbuildings in parcel sketch.
If first added in the site plan, then add any future outbuildings in the site plan.

Error One:
If the user attempts to add a building in the Parcel Sketch tab and there is NO house sketch, they will get the following error:

Improvement MUST be added in the Site Plan.

Error Two:
If the user attempts to add a building in the Parcel Sketch and the existing outbuildings were originally added in the Site Plan tab, they will get the following error:

Subsequent buildings MUST be added in the Site Plan as well.