PROC EXPORT with DBMS=XLSX can add/update a sheet within an existing XLSX file. That's a relatively recent feature, added in SAS 9.4.  DBMS=XLSX works on Windows and Unix/Linux, and does not require any additional Microsoft code libraries or PC Files Server.   Remember, PROC EXPORT with DBMS=XLSX require the SAS/ACCESS to PC Files license/install.  If you're using SAS University Edition, this has everything that you need.   See a full example in this blog post.     ... View more