How to add a modifier to a nested document with mongodb

For my comments it was pretty easy …

return await PostModel.findByIdAndUpdate(
     post_ID,
      {
        $addToSet: {
          comments: {
            creatorId: req.body.creatorId,
            creator: req.body.creator,
            body: req.body.body,
            likes: [],
            replies: [],
            timestamp: new Date().getTime(),
          },
        },
      },
      { new: true },
      (err, docs) => {
        if (!err) return res.send({ docs });
        else return res.status(400).send(err);
      }
    );

I wanna do the same with my replies , but I cant access it chrome-capture