The lawbyte 807 update can be installed on top of lawbyte 806 or lawbyte 805 as the file structures have not changed between these releases.
However lawbyte 807 should not be installed on top of lawbyte 804 (or earlier) - in this case it is necessary to install the lawbyte 805 update (which contains a file restructuring utility)
If in doubt please contact lawbyte support on 01253 290300