Multiple Event Handling for the Lazy Ones

why not just create a custom handler for all the textboxes?

 addhandler textbox1.textchanged, addressof textchangedhandler
 addhandler textbox2.textchanged, addressof textchangedhandler
 ....
 'add additional textbox handlers
 ....
 addhandler textbox7.textchanged, addressof textchangedhandler

For the customer handling routine

 private sub TextchangedHandler(ByVal sender As System.Object, ByVal e As System.EventArgs)
  '....
  'Do sub code
  '....
 end sub