Thats a feature in 2.14 I beleive
VMware App Volumes 2.14 Release Notes
You can share Writable Volumes across vCenters using Shared Datastores and the users can access their Writable Volumes from multiple vCenters with a Shared Datastore. In larger deployments, end user persistence is no longer pinned to a specific vCenter. A user can use their Writable Volume in one session, log out and log in to a session on another vCenter and continue to use their volume.