Autodesk Infrastructure Studio can load only CAD layers from a DWG file. These CAD layers are translated to individual SDF feature classes within a single SDF feature source. If you have xrefs in your DWG, the layers from the externally referenced files can also be loaded.
DWG files are loaded one at a time. If you have more than one file in the load procedure, the different files are loaded sequentially. For example, if you have several DWG files in the procedure, you will get several resources, each one of which contains the layers of a single drawing, not one resource containing all the layers of all the drawings together.