Deduct 1% from PayPal Request Order v2 API Request

I hope everyone is in good health.

I operate a website that connects various merchants, allowing them to receive payments from their customers. I want to implement a system where, if a merchant requests $100 from a customer, 1% of that amount is sent to my account. The remaining amount, after deducting the payment fee and the 1% commission, should be sent to the merchant's account.

For example:

Invoice Request: 100$

PayPal Fee: 3.98$

1% of 100$: 1$

Remaining Amount: 100 - 3.98 - 1 = 95.02$

So 1$ should sent to owner account

98.05$ should sent to merchant

Also, How can I add custom variables to this Order so I can get those values using below API request.

https://api-m.sandbox.paypal.com/v2/checkout/orders/1CH72974UG290335P/capture

& when the customer paid the requested amount then sandbox should be called.

I want to know how can I enable webhook, add 1% deduction, and can add custom variables.

Updated Order v2, After reading out comments.

curl --location 'https://api-m.sandbox.paypal.com/v2/checkout/orders' \
--header 'Content-Type: application/json' \
--header 'PayPal-Request-Id: paypal-request-id-1-sandbox' \
--header 'Authorization: Bearer A11AAJl4blmlkUnocTX2KQYUdm2gz3d94isr2tL6RvemrN49bPCmI_d5EzvhdZAqOTLl-nxIycCfdaGGvHljfnhtPR2fl_CJA' \
--header 'PayPal-Partner-Attribution-ID: TEST_SP_PPCP' \
--data-raw '{
   "intent": "CAPTURE",
   "purchase_units": [
      {
         "custom_id": "customer_paying_against_invoice_using_order_v2=1_=_company_auto_id=1_=_job_auto_id=181",
         "amount": {
            "currency_code": "USD",
            "value": "100.00",
            "breakdown": {
               "item_total": {
                  "currency_code": "USD",
                  "value": "100.00"
               }
            }
         },
         "payee": {
            "email_address": "sb-xyz@business.example.com",
            "merchant_id": "L6HQNC247QXGQ"
         },
         "platform_fees": [
            {
               "amount": {
                  "currency_code": "USD",
                  "value": "1.00"
               },
               "payee": {
                  "email_address": "sb-abc@business.example.com",
                  "merchant_id": "4LZCA37NTSXH4"
               }
            }
         ],
         "items": [
            {
               "name": "Invoice 1 - Test Job",
               "description": "-",
               "unit_amount": {
                  "currency_code": "USD",
                  "value": "100.00"
               },
               "quantity": "1"
            }
         ]
      }
   ],
   "payment_source": {
      "paypal": {
         "experience_context": {
            "payment_method_preference": "IMMEDIATE_PAYMENT_REQUIRED",
            "brand_name": "Project Name",
            "locale": "en-US",
            "landing_page": "LOGIN",
            "user_action": "PAY_NOW",
            "return_url": "https://test.com/pay.php?paypal_return_url=1",
            "cancel_url": "https://test.com/pay.php?cancel_url=1"
         }
      }
   }
}'

If you are approved as a PayPal partner/platform, which is only a possibility for some, the cleanest solution is to onboard sellers with third_party_details.features.PARTNER_FEE specified.

If a seller is onboarded that way, you will be able to specify a partner_fee amount in the v2/checkout/orders API call.

If you are not approved as a PayPal partner, options are limited and there are no good ones worth going into detail about.