GGCS is a member of the ERGaR Certificate of Origin (CoO) Scheme. The Scheme allows participating registries to transfer RGGOs and equivalent certificates between their registries although not all members of the Scheme will allow transfers of certificates with all other members.
The GGCS has a guidance document on transfers to and from other registries which can be accessed here - Guidance Documents.
More information on the ERGaR CoO Scheme and its current membership can be found on the ERGaR website here - Home - ERGaR