If you already have elevation certificates for each building (only one building may appear on any Elevation Certificate) and they all qualify for a Letter of Map Amendment (LOMA), then you can submit separate LOMA applications for each building.
If you don’t have Elevation Certificates for each building and the entire lot qualifies for a LOMA, then you may apply for a LOMA that reclassifies the entire lot as being in a different flood zone, which would include all structures on that parcel. The key to filing such an application, is that instead of the Lowest Adjacent Grade next to a building needing to be higher than the flood level, the lowest point on the entire lot must be higher. You’ll need a land surveyor to complete a special Federal Emergency Management Agency (FEMA) Elevation Form.
Note: An Elevation Form differs from an Elevation Certificate, and not all surveyors may be familiar with the latter.