Actor Sequence Component and Bound Actors

I’m creating a “stage” blueprint actor. This stage has placeholders, where different Actors (“stage actors”) will be played.
Now, I want to create a stage-specific Sequence that uses Cine Camera to focus on these actors in turn.
I can create the Cine Camera track, and the Tracking Focus Actor keys, in the Sequence.
However, when I do so, it says “Unresolved Binding” and the “Track …” green button with the plus, does not have any way to add an object binding.
When doing this for a Level Sequence, I can add them because the Track+ button has many more options.

What I want to do is to call a function on this blueprint to set the intended "stage actor’ actors, have the blueprint configure the Sequence with the respective Actors, and then have the Focus track update the property based on these configured Actors when playing.

How can I accomplish what I want to do?

sequencer for actor doesnt have add binding.jpg