Here's a procedure I did for my daughter to permit the user to add records on the fly to a conbo box using a data table and the procedure adds the inserted data to the table.
This routine will let you add data to a table on which a combo box is based, on the fly. For example, the "bates" table contains numbers and a name. To add a new name to the table while entering data on the form, this routine is attached to a command button (command5) which opens a dialog box for entry of the new name, then adds the new name to the existing table "bates" in the field "name". The combo box must be based upon the table "bates", and "name" must be selected as the listbox field. The same routine can be used to add data to any table in the selected database and recordset.
Private Sub Command5_Click()
Dim varName As Variant 'variable must be declared
varName = InputBox("Enter New Name"
Dim db As Database 'The "AddNew" function works with a recordset, so these
Dim rst As Recordset 'settings are required to make it work.
Set db = CurrentDb
Set rst = db.OpenRecordset("bates", dbOpenDynaset)
With rst
.AddNew
!name = varName
.Update
Me.cboList.Requery 'may not be essential sine this is a table not a query
End With 'probably not a bad idea to include just in case to use
End Sub 'a query rather than a table
Good luck!