Does anyone know what the "FinancialEventGroupId"s are?
Amazon MWS Documentation describes them as “A unique identifier for the financial event group.” but I can’t find these identifiers.
Can anyone help?
You can’t find them where? Need more information to help
If you make a call to ListFinancialEventGroups, the results will contain FinancialEventGroupList where each one of those has a FinancialEventGroupId.