Addnew or NewRow event for Datagrid?

[PrimusGreg]

I have a datagrid in which I've applied a gridstyle so that I'm only displaying 4 out of 8 fields in my dataset. The user enters information into those 4 cells and then moves to the next row which adds a new record to the dataset. Above the datagrid I have textboxes that the user enters in the information that fills the other 4 fields that are not displayed. I did it this way because these 4 values will be common to every record entered into the datagrid. So, here's my dilema: I need to know how I can enter the data from the textboxes into the values for the dataset before I move to the new record. The event has to occur before it moves to the next record because an error is thrown if I don't assign values into all the fields that don't accept null values. Any ideas?