Create Facebook style notifications (Laravel)

I am using the standard laravel notifications setup and it's working great but now I want to customize it further.

How can I get the Facebook format for creating notifications? For example if a notification for comment on a post already exists, now instead of creating a new one, I would like to append to it, increment the count and update it.

Basic use cases

original notification:

$user->name . ' left a comment on your post';

updated notification:

$user->name .','. $otherUser->name . ' and 3 others left a comment on your post';

I don't have any codes yet because I don't really know from where to start making something like this.

via Chebli Mohamed