Ionic3 PayPal multi Merchant

Hello,
I am trying to create multi stores where different merchants should sell their products and each merchant must use his own PayPal account.
I would like to jump in the PayPal form with checkout data and merchant id as well in order to get the payment in the correct merchant id for each store.

In a desktop web site I used the below action post for each merchant and it works fine:

action: “https://www.paypal.com/it/cgi-bin/webscr
param1: name=business and value=“xxxxxxx”
param2: …
etc…

In ionic3 I’m trying to use a new PayPal javascript sdk.

1 - I call my client ID in the index.html header as below:
2 - In the PayPal button I tried to pass the merchant id of each store in the payee command but PayPal, but I get an error: Pass merchant-id=“XYZ” in the PayPal script tag. Pass merchant-id=unknown if you do not have access to the merchant id. Obviously I have the merchant id that I pass in the payee command as you can see in the below script. Where am I wrong?

below my button script:

initPayPal() {
var _totaleOrdine = this.totaleOrdine.toString();

var _merchant: string = 'XXXXXXXXX';

  paypal.Buttons({
    env: 'sandbox', // sandbox | production
      locale: 'it_IT',

      //ref: https://developer.paypal.com/docs/integration/direct/express-checkout/integration-jsv4/customize-button/
    style: {
        size: 'responsive',
        color: 'gold',
        shape: 'pill',
        label: 'buynow', //                    label: checkout, buynow, credit, pay, paypal
        tagline: false

      },

    commit: true,
    debug: true,

     createOrder: function(data, actions) {
      // Set up the transaction
        console.log(data);
        console.log(actions);

        return actions.order.create({

        application_context: {
            brand_name: "MyBrand",
        },


        purchase_units: [{

     //   reference_id:_merchant,

          amount: {
            value: _totaleOrdine,
          },

          payee: {
            email: 'merchant2@mydomain.it',
            merchant_id: 'xxxxx'
          },

          shipping: {
            address: {

                address_line_1: "Via Roma 10",
                address_line_2: "",
                admin_area_2: "Roma",
                admin_area_1: "RM",
                postal_code: "00100",
                country_code: "IT",

            },

            name:{
                full_name: "adam adami"
            },
          },

        }],
});
},
     onApprove: function(data, actions) {
      return actions.order.capture().then(function(details) {
        alert('Transaction completed by ' + details.payer.name.given_name);
       console.log(details);
        // Call your server to save the transaction
        return fetch('/paypal-transaction-complete', {
          method: 'post',
          body: JSON.stringify({
            orderID: data.orderID
          })
        });
        //
      });

    },

     onCancel: function(data, actions) {
        /*
         * Buyer cancelled the payment
         */
         console.log("Buyer cancelled the payment");
      },

     onError: function(err) {
        /*
         * An error occurred during the transaction
         */
         console.log(err);
         console.log("An error occurred during the transaction");
      }

  }).render(this.paypalbuttoncontainer2);