Laravel 4加载与最新和另一个条件的关系

Hi guys I have here a small code that will load a user status with latest. My question is how can I extend this so that when example user 1 and user 2 are the same department id of 2 they can see there statuses. Just like facebook, when user 1 is friend with user 2, user 1 can see user 2 status and user 2 can also see user 1 status.

$user = Auth::user()->load(['statuses' => function($status)
{
    $status->latest();
}]);

TIA :)

Department hasMany Users, and I assume User hasMany Statuses, so this will work:

// Department
public function statuses()
{
  return $this->hasManyThrough('Status', 'User');
}

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

// User
public function department()
{
  return $this->belongsTo('Department');
}

// usage
$statuses = Auth::user()->department->statuses()->with('user')->latest()->get();