get two users in a post in laravel

i have a users table with many users.example 1:mike, 2:nina, 3:john. and i have a posts table with user_id, which is the original creator of the post. and then i editors who can edit the post later on. any user can lock or open. thus if a post is locked only he can edit it while it is locked. so i have a field named locked_user_id in the posts table. I can have the laravel relationships as follows.

in User model:

public function posts(){
        return $this->hasMany('App\Post');
    }

in Post model:

public function user(){
        return $this->belongsTo('App\User');
    }

i can retrieve the author easily by

$posts->user->name

but how do i assume locked_user_id is a username id, and get its value, such as the name of the user who locked the post. can be the author at first and editor later on.

via Chebli Mohamed