|I'm not sure what you are asking. You want to allow the user to change one cell and have the other date cells update, but you don't want the user to be able to change them... is that correct?|
If so then do something like this
A6 = today()
A7 = A6+1
A8 = A7+1
protect all of the cells that follow A6. Now when someone enters a date in A6 the other cells will update automatically.