To import new empty feature classes from the clean GBAGIS.mdb, or from any external geodatabase, you should use the Convert Feature Class tool available on the Lucity GIS toolbar in ArcCatalog.
Using this tool ensures that the new feature class you import shares the same domain and spatial reference as the feature dataset you import it into. If you simply copy and paste a new feature class into your feature dataset, you will not have this assurance.
Lucity does not automatically add feature datasets to your geodatabases. If you want to utilize any new feature classes or feature datasets, you can use this tool to load them into your existing geodatabases.