include有办法和模型定义的关联不同名吗？

比如我想要在同一个includeTarget下面，根据类型返回不同对象，要怎么实现呢
transformer中includeTarget

public function includeTarget (Message $msg) {
    if ($msg->type == 1){
        return $this->item($msg->marchantTarget, new MarchantTargetTransformer());
    } else {
        return $this->item($msg->userTarget, new UserTargetTransformer());
    }
}

model中

public function marchantTarget(){
    return $this->belongsTo(Marchant::class, 'target_id');
}
public function userTarget(){
    return $this->belongsTo(User::class, 'target_id');
}