Saving into 1 workbook as a different worksheet
 

I am exporting Crystal reports into excel workbooks but want to save them
into the same workbook as diferent daily woorksheets all in the same work
book. Everytime the scheduled export runs it overwrites the entire workbook.
Is there a way to change the syntax of the file name at save time to alow it
to be saved into an existing workbook as a new worksheet?