I think that you may need to provide a few more details about what you are trying to do and why. Is there any reason you can't simply run a template to create the new file? Also, the Copy Tree function works really well with copying files and re-establishing serial numbers for file names, so you may want to look at that also. So without knowing why you choose to go with dispatch, I'll offer up this suggestion.
Could you set the file data card to automatically pull in that serial number into an edit box by default, then have dispatch copy the source file, check it in, read what the new serial number is on the card after it has been created and then re-name it to that value? I haven't tested to see if the dispatch copy function would allow the default serial number to be populated on the new files data card, but it would be worth a shot.
Derek M. Lawson