how do you display a sub scene in the timeline?

a camera is rendering to a render texture inside a sub scene
that sub scene is animated via its own timeline
the super scene has a timeline which uses a storyboard virtual camera to cross fade from the sub scene
this storyboard shows nothing or just what was last rendered by the subscene's camera
no animation
also particles only render if the particlesystems are selected while playing the timeline of the subscene.

 

So far this is the only post of keywords `Timeline` & `Subscene` I can dig.

More precisely I'd like to know about using Timeline with entities under subscene.

AFAIK, the Dots Timeline is WIP for quite a few time I think. And there's a package named `com.unity.timeline.dots`, which is absolutely obscure and not even a thread says it was put in used by anyone.

https://docs.unity3d.com/Packages/com.unity.timeline.dots@0.8/manual/index.html