In the Dutch energy sector, grid operators aren’t competitors—they jointly maintain critical national infrastructure and must collaborate closely. When the mandate came to build a shared Microsoft Entra ID tenant where multiple organizations could work together securely, the team had to rethink many assumptions about B2B collaboration.

This discussion walks through the architecture and security decisions behind a production multi-organization resource tenant where every user, including administrators, is a B2B guest from their own home tenant and no local identities exist. We’ll address how access governance was structured using Entitlement Management, how Conditional Access was designed for multiple audiences and trust levels, and what tenant hardening looks like when no single organization “owns” the users. Attendees will see the practical problems encountered along the way and how they were solved. If you’ve ever had to design identity architecture for shared tenants where security can’t be an afterthought, this session is for you.