We would like to define some organizational units within our company,  each having separate customers, products, invoices, etc, but sharing the same COA, since they are still part of the same legal entity.

I was thinking I could create multiple companies and uncheck the box "This company has its own chart of accounts" in the accounting settings. I was assuming then when unchecked, Odoo would just use the COA of the parent company, but this seems not to be the case. Whatever I try to do I get warnings that I first have to define a COA for the company or I'm not able to select any accounts.

Can someone explain the purpose of the checkbox "This company has its own chart of accounts" if it's not possible to use a company without it's own COA?