I always start mine with:
"this is a supplemental report to one filed mm/dd/yyy"
and then I do the whole deal. Who, What, Where, Why, When, How.
Usually a brief "previous activity reported: blah blah"
then "current activity being reported: blah blah"
"this is a grand total of $XX from XX to XX"
My opinions are my own, and not that of my employer.