Create custom content type as post/newsfeed type

Situation

We can see that default post on the Activity stream has a simple field with Text and Visibility. I am also aware that we can just add new fields to the Post Setting.
Also, there are Social content types labeled as Topic and Event available. Once a user added a content using Social content type or the post, it will be displayed in the Activity stream or newsfeed, we can say.

Problem/Motivation

Is it possible to create a custom content type as a new Activity stream type? Once a content is created, this will also display in the Activity stream.

What I've done so far

I tried to duplicate the Topic but with my custom fields with the following steps:
1. Created a custom content type named Test
2. Configured "Mange Display" fields(same with Topic).
2A. Added "Custom display setting" Activity, Activity comment, Search Index, Small teaser and Teaser.
3. Added Message Template(same content with Topic)

Now when I try to add a new content as Test, the node is created but it is not displaying in the newsfeed. Are there any other steps I need to do to accomplish this?

I would appreciate if anyone can suggest if encountered the same scenario as this. Thanks for your help in advance!