Rebecca Sell 6/9/2015 9:26:15 AM
Thanks, that does the trick.
I also set up a table of MONTH, each MONTH record holding the previous month as a field (eg month record 201505 has a field for the prev month of 201504).
Then a multi-reference link, as you say, to the same table, bringing in the previous month reference, and then finding the data from those records as a summary.
It works, an automatically updates changes in previous months.