@McHenry screenshot the GENERAL tab of "Disaster Recovery" SR please
just to see how many VDIs it hosts
it was announced here
https://xen-orchestra.com/blog/xen-orchestra-6-3/#-backup
but it is not explaing in details, I gathered information in another topix in this forum from @florent
you also have the Changelog of 6.3.0
https://github.com/vatesfr/xen-orchestra/blob/master/CHANGELOG.md#630-2026-03-31
points to PR9324
[Replication] Reuse the same VM as an incremental replication target (PR #9524)