Ok, latest CB Activity build release can now suppress the original activity post when a reaction post is on the same page.

I've made additional improvements to the grouping behavior display of activity as well to let several remain interactable.

I've also implemented support for Like Bumping. This would bump a post if someone likes the post to the top of the stream.

For your site I recommend setting the following in CB Activity > Parameters > Activity.

Comments
Reply: Disabled
Like: Disabled
Mention: Disabled

Activity
Comment Bump: Enabled
Comment: Disabled
Tag: Disabled
Like Bump: Enabled
Like: Disabled
Mention: Disabled

This should reduce the amount of activity generated and allow interactions to push the post back to the top of the stream. You may also want to adjust the following.

CB Activity > Parameters > Streams
Grouping
Days: 30

This will allow similar activity merging to extend up to 30 days instead of 10. This might be necessary if your site isn't really generating enough activity to fill out the feed.

You can delete existing activity from CB Activity > Activity to clean up the current stream.

If you're still having issues please PM backend super user login credentials and will take a look at your configuration and make some recommendations as well as see why grouping may not be working.

If someone creates a post - it is added at the top of the stream

That's already the case since new posts are always at the top.

if someone posts some pictures to their gallery - that is added to the top of the stream

That's doable with gallery activity.

If someone posts a comment on an article or a photo, or someone likes an article or a photo - that article/photo goes to the top of the stream (but does not leave the original post in the stream)

When you say likes an article or a photo do you mean likes the article or photo activity entry or likes the article or photo directly? For posts that should be the case now if both Comment Bumping and Like Bumping are enabled.

Will review additional grouping behavior for other activity. I cannot group comment and like activity together though so if you have both comment activity and like activity enabled you can end up with 2 entries. It just wouldn't make sense to group those as they're 2 different interactions. So I'm not sure what would be best to do there.

There's a few cases were grouping can't apply. For example I upload 6 photos. Someone comments on 1. Comment activity is generated for that 1. Then suppressing the original post where I shared 6 photos wouldn't make sense. Will try to improve this for other post types since the original post suppression behavior was implemented only for activity interactions.

Ok, believe I have possible solution for the issue of a comment and like activity both existing one after another. I'm currently implementing a parameter to toggle the suppression of the original post, which was just implemented so this can be turned off.

I am also adding a Suppress Duplicates parameter. This will check if a post of an object type already exists and if it does all subsequent similar posts will be removed. So for example if you have the following.

gallery.photos.123.comment
gallery.photos.123.like
gallery.photos.123

With Suppress Original you'd see the following.

gallery.photos.123.comment
gallery.photos.123.like

With Suppress Duplicates you'd see the following.

gallery.photos.123.comment
gallery.photos.123

With Suppress Original AND Suppress Duplicates you'd see the following.

gallery.photos.123.comment

At the time this is the best solution I can provide for aggregating these posts together. This will be available probably tomorrow as I need to do plenty of testing. Suppress Original will be default Enabled, but Suppress Duplicates will be default Disabled. Both will only apply to activity and not notifications.

The new suppression behavior is now implemented in latest CB Activity build release. It can be enabled in CB Activity > Parameters > Streams > Grouping. For your usecase you'd enable both Suppress Original and Suppress Duplicates.

Additionally the registration activity logging and notification logging have been fixed.