MainChannel->GroupChannel->Channel->Activities

    OnlineChannels->SocialMedia->Youtube->Activities
    OnlineChannels->SocialMedia->Facebook->Activities
    OnlineChannels->Webpages->Something.com->Activities
    OfflineChannels->Face-To-Face->Congress->Activities

id  |  name  |  lft  |  rgt  |  depth  |  color  |  important_links  | parent_id

$GroupChannels = Channel::where('depth', 2)->with(
                    'parent',
                    'children',
                    'children.activities'
                );

if(isset($input['filtered_channels'])){
        $Channels = $Channels->whereIn('id', $input['filtered_channels']);
    }
    $Channels = $Channels->get();

foreach($GroupChannels as $Channel){
        foreach($Channel->children as $Subchannel){
            foreach ($Subchannel->activities as $Activity){
                $removeActivity = false;
                // do some checks on the activity that will maybe turn the $removeActivity to true
                if($removeActivity){
                    $Subchannel->forget($Activity);
                }
            }
        //forget Subchannel if not Activities remain
        }
    //forget Channel if not Subchannels remain
    }

class Channel extends Model
{
use CrudTrait;
use SoftDeletes;
use VenturecraftRevisionableRevisionableTrait;
/*
|--------------------------------------------------------------------------
| GLOBAL VARIABLES
|--------------------------------------------------------------------------
*/

protected $table = 'channels';
protected $primaryKey = 'id';
protected $fillable = ['name', 'color', 'parent_id', 'lft', 'rgt', 'depth', 'important_links'];
protected $dates = ['created_at', 'updated_at', 'deleted_at'];

/*
|--------------------------------------------------------------------------
| FUNCTIONS
|--------------------------------------------------------------------------
*/
public static function boot()
{
    parent::boot();
}
/*
|--------------------------------------------------------------------------
| RELATIONS
|--------------------------------------------------------------------------
*/
public function activities()
{
    return $this->belongsToMany(Activity::class);
}
public function children()
{
    return $this->hasMany(Channel::class, 'parent_id', 'id');
}
public function parent()
{
    return $this->hasOne(Channel::class, 'id', 'parent_id');
}

/*
|--------------------------------------------------------------------------
| ACCESORS
|--------------------------------------------------------------------------
*/
public function getChildrenAttribute(){
    return $this->children()->orderBy('lft');
}
}

HasMany {#872 ▼
      #foreignKey: "channels.parent_id"
      #localKey: "id"
      #query: Builder {#831 ▶}
      #parent: Channel {#840 ▶}
      #related: Channel {#832 ▶}
    }