I would just like to make sure that i am reading the below correctly, once you have multiple orgs you wont be able to use auto-vpn, that is my general understand, you will have to use non-meraki site-to-site vpn
Each organization represents a separate SD-WAN instance. Meraki SD-WAN is implemented through use of Meraki Auto VPN technology. Auto VPN is an extremely low-touch solution for creating SD-WAN networks, by automatically networking all sites in a single organization. Because of this, multi-organization deployments are also multi-SD-WAN-domain deployments. Usually this is preferred for customers with needs for multiple organizations, but it should be noted in design.