How to add additional field, such as First Name and Last Name in Back in Stock form?

Hi team,

I have implemented the Back in Stock in my Shopify store.

However, I would like users to be able to enter their first name and last name as well.

It seems I can add html in the body_content like this:
     body_content: `
          Register to receive a notification when this item comes back in stock.
          <div>
            <label for="name">Name:</label>
            <input type="text" id="name" name="name" placeholder="Enter your name">
          </div>
          <div>
            <label for="email">Email:</label>
            <input type="email" id="email" name="email" placeholder="Enter your email">
          </div>
        `,
However, I could not figure out how to send the values of the two fields when submit.

For Sign-up forms, i can created customized fields and get their ids.

Is there any APIs i can use?

Could you please advise me how should I do it please?

Besides, the Add me to your email list seems not working properly.

My list structure is:
 

It should have name, email and etc.

But in the Back in stock form only has an email field.

I have tried many time and it failed to record info into my list.

Could you please help?

Thank you.