Yes, thats right!
Okay, that's where tristaanogre and I got confused then. It sounded to us like you were generating a user id inside your first test and then storing it in Excel for use in other tests.
Let's backup a bit. Could you set up your tests like this? Then you would be leveraging the DDT loop instead of trying to go around it. This would read a record from Excel, do stuff with it, then loop around and get a new record and do the same stuff with the new data, again and again until it's out of lines in Excel.
DDT loop on Excel file
test for adding user
test for login with new user
other tests
DDT next
