When submitting on a DIY form or custom eCommerce page, the Data Source should automatically fill in certain values. For example, if the form uses a BBMS processor, the transaction should receive the value "BBMS Online Gift" in the Data Source field.
We are currently evaluating this issue and will update this article when we have more information.
In the meantime, we have built a utility that will add these values to the transactions until we can release a fix. The utility will run automatically every hour and add the Data Source to transactions that were created the hour before. It will continue to run until we release the fix.