Combining join 2 STL files using solidworks.

I like to join 2 STL files using solidworks.  The STL files may or may not be from solidowrks part file.  I just want to align and or move the files before combining them to create a new STL file.  If i can save them as a part file thats even better but i dont think SW is able to join 2 faceted files and create a solid part.

Thanks in advance

SolidworksParts And Features