MorphMany or multiple manyToMany

Hi!

I need help structuring adding comment feature

DB schema for part of the app, there are aprox 20 more tables

departments

    id - integer
    name - string
    ...

users
    id - integer
    name - string
    ...
 
events
    id - integer
    title - string
    ...
 
goals
    id - integer
    goal - string
    ...

Relationships

Department hasMany Users
User hasMany Events
Event many To many goals

I now want to add the feature comments. PolyMorphic would be easy to add comments on department, user.

But it should be possible to comment on goals, and I want the comment to be associated to the user. So that other users can not see these comments. Should be private to the user.

Strategies. 1. Add extra column with user_id to the commentable table

commentable
    comment_id - `foreignId('comments')->constrained()`
    commentable_id - integer (ID of goal, event, department, user)
    commentable_id_type - string (Model name, like "App\Models\Goal")
	user_id - foreignId('users')->constrained()`

With the risk that this will involve more complexity to the code, will it work with laravel Eloquent, or will it need Raw SQL querys.

Or Separate the comments for eg goal and some other table that have more complex ralation to user and make manyToMany relationships and more tables.

Suggestions, previous experience to share?

Thx in advance! Tobias