Is there a way to add users as Viewer after tempo event is created. I do not see

HI Sarvana,
You can use participant icon to add user as participant for post ,So that they can get all updates of your post.Please refer attachment.

This link might be helpful

ajinkyab277 and Sam, I appreciate your response on this. I was forgot to mention taht I am looking for add participant via plug-in rather than manually.

@saravanana Hi, to the best of my knowledge, only two solutions are viable as of now:
1. Creating a new event with a new set of participants when there is a change in the participants of the news entry.
2. Using Appian Group objects (created dynamically for solely managing the security of the feed in the corresponding case) to target the news entry security.