2 part question:

a. What events should I be using to update between my userform and
worksheet? Is it ever good practice to use the ControlSource property for
say a textbox?

b. How can I validate multiple textbox's with the same code? For example:
Private Sub TextBox1_Change()
Call Update
End Sub

Private Sub TextBox2_Change()
Call Update
End Sub

In Sub Update(), how do I reference which text box changed?

thanks,
Steve