This article explains how to add a Transitional Serial Number to a building with an existing Serial Number. Transitional Serial Numbers can associate the building with a past/old SN. You must have a building that is Processed and already has an SN
Click on the Buildings List via System>Lists>Buildings
Search the building’s Serial Number
Hover on Three dots of the building
Select Update
Click on Transitional Serial Number
Add Transitional Serial Number
Update