You want different parts of the same file sorted independently in one step? Yes, it can be done. If you thought INCLUDE would help, perhaps you can either explain how, or you can review what INCLUDE does in the documentation.
How you do it is extend your record by the longest value you want to SORT on. Conditionally put the correct data for the correct record into the key field. You do this in INREC, and then you SORT. In OUTREC or OUTFIL you return the record to its original size using BUILD.