Access 2007 has a new property for Memo fields so you can append only but
not edit/delete existing data in the field.
If this is a memo field in previous versions, you might want to consider
breaking this into a related table. A user can then add more notes (i.e.
another record) at any time, but not edit or delete existing notes. This has
the added advantage that you can track who wrote each not and when.
If neither of those approaches are suitable, you could use two text boxes
for this field:
a) One bound to the field, with its Locked property set to Yes.
b) An unbound one below it, where the user can write their additional
comment.
Use the AfterUpdate event procedure of the unbound text box to append the
value to the bound one, e.g.:
Me.Comment = Me.Comment & vbCrLf & Me.Text1
