Hi Mr. D,
Please look whether below setup would be useful or not.
1) Create Data Source
2) Create Infocube. Use this as staging infoprovider for bpc loading
3) Use either "Append" or " Overwrite records with match key" in Transaction data DM package during data loading into BPC.
Lets assume you wanted to load current month data. Select the required month in "Set Selection" button under infoprovider in DM package. If you want to run for same month with updated records, then select "Overwrite records with match key".
Regards,
Venkat