IF - GF: Are partner organisations in a third country also subject to audits?

Partner Organisations are not considered third parties or subcontractors using the formal definitions of those from the Grant Agreement, so REA cannot audit them.
It is the beneficiary in the Global Fellowship who is responsible for the entire fellowship. Thus, it is up to them to show that the fellow actually spent the Person Months in the partner organisation. It is recommended to be written into the partnership agreement between the beneficiary and the partner organisation.