To add serial numbers to the products in ERPAG, do the following steps:
1. Your beginning inventory for those products should be 0.
2. Your products need to be set that they are tracked by a serial number.
3. Go to inventory > stock adjustment > create > import data > beginning inventory.
4. Just copy/paste the columns from your xls to ERPAG.
5. Save the changes and do the stock adjustment, and the serial numbers will be added to your inventory.