function addDataResponse(
    address seller,
    address notary,
    string dataHash
  ) public onlyOwner validAddress(seller) validAddress(notary) returns (bool) {
    require(orderStatus == OrderStatus.NotaryAdded);
    require(transactionCompletedAt == 0);
    require(!hasSellerBeenAccepted(seller));
    require(hasNotaryBeenAdded(notary));

    sellerInfo[seller] = SellerInfo(
      notary,
      dataHash,
      uint32(block.timestamp),
      0,
      DataResponseStatus.DataResponseAdded
    );

    sellers.push(seller);

    return true;
  }