I want to generate Financial Reports based on both the GAAP and IFRS reporting standards.

One of the requirements is to sum balances from several individual accounts used in our GAAP report and shown them as a single balance in our IFRS report.

If I have five expense accounts under GAAP but wanted a single balance under IFRS how would I do this in Odoo?

I have been reading https://www.odoo.com/documentation/19.0/applications/finance/accounting/reporting/customize.html and it seems that perhaps I can tag the accounts and define our IFRS reports to group by the Tag?

The Line Grouping part of the documentation discusses creating a new field on the Journal Item but I am unsure if this is the correct approach and have not been able to create a Tag based field due to the error "Field x_tag_ids of account.move.line cannot be used in a groupby expression."