Replying to message with single emoji should be displayed as emoji next to the original message.
For example, if I respond with or emoji to a message, the recipient should see it as “like” on message, not as new message. Only one emoji should be attached to the original message.
As far as I know, reactions will be introduced in one of the next releases.
The current version for Android already has this as an experimental feature.
That’s already implemented. In the current Android-App as experimental.
And for all other Apps it will come soon