Accept reusable canvas sources that are referenced by an existing parent plugin, matching the post-#2546 scaffolding guidance, while continuing to reject orphaned sources. Cover parent-only, standalone, and orphaned registrations.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 52be9c67-3ae4-4610-93d0-fe0b7ab95ccb
Jenny Ferries