Treat these as separate changes. Moving billing ownership alone does not change the Entra directory or Azure DevOps organization, so repositories and Boards remain. Changing the subscription directory removes Azure RBAC assignments and custom roles; service principals, managed identities, Key Vault access, and pipeline service connections can break.
For the merger, keep the existing Azure DevOps organization and connect it to the target company’s Entra tenant; there is no supported organization merge. Before switching, ensure a target-tenant member is a Project Collection Administrator, export users, map identities, invite required guests, and request SSH-key cleanup through Support. Microsoft recommends Support when more than 100 users must be remapped.
Freeze deployments during the change. Export RBAC and service-connection inventories, then validate sign-in, groups, licenses, pipelines, agent pools, feeds, extensions, and federated credentials. If transferring billing only, leave the directory unchanged. If changing directory, re-create Azure roles and identities before production deployments resume.