Try creating a cursor in Load event of your form containing that three
fields. Then in the InterActiveChange event of your combobox, your code will be something like this :

Select (cursorname)
Replace custid With this.List(ListIndex,1),;
custname With this.List(ListIndex,2),;
comments With this.List(ListIndex,3)

Thisform.Refresh()

The editbox is still the CurrentControl of the third column and the RecordSource of your grid will be the name of the cursor you created.

HTH