Import STEP file with 774 parts. Help converting to assembly.

I have a STEP file from a vendor that contains 774 parts.  I want to get this into a solidworks assembly.  I have tried:

1.  importing it into an assembly.  SolidWorks doesn't allow it.

2.  I have tried opening it as a multibody part.  Then I try to use "Save Bodies" or "Split" command to create the individual part files.  This fails because SolidWorks tries to open every part that is saved.  So it tries to open 774 parts which crashes SolidWorks.

Hunches:

1.  Use a macro to save the individual parts?

How can I get this step file to an Assembly so that I can use "Large Assembly" mode?

SolidworksImport export