diff --git a/public-docs/plugins/providers.md b/public-docs/plugins/providers.md
index 6fbe766c61..1a1359b098 100644
--- a/public-docs/plugins/providers.md
+++ b/public-docs/plugins/providers.md
@@ -289,7 +289,8 @@ servers during `session.open`. There is no separate reload operation.
 
 Use `restoration: "core"` when Paseo can reopen a session from persistence. A provider-owned child
 uses `restoration: "parent"`; emit it as another `session.opened` event with `parentSessionId` and
-recreate it while restoring the parent.
+recreate it while restoring the parent. The parent's `session.opened` capabilities must include
+`session.subsession`. Paseo fails the whole connection when a parent without it opens a child.
 
 ## Add commands and steering