good 'ol chicken / egg cyndrome
Personally I would never put my add inside the grid. Now you know why. The only option is to replace the sqlDataSource with a dataTable and maintain a dummy record around to populate the grid. Or logic that create the dummy record under those circumstances.
Another solution is to place the add button outside the grid. Other than this...
Interesting to note that the grid has no built in functionality for insert at least not button command. It has to be hacked in. Ever wonder why?
Sorry,