Is there a way to convert an assembly into a single part file?  I got a solid model sent to me as a STEP file and when I open it there is 6 sub assemblies, with many parts in each sub assembly.  I just need to be able to place it in my main assembly, but because it's a STEP file there are no mates which causes the pieces to move if you grab them.  Us there a way to somehow convert it into a single part?