Hello Shriram,

Not sure if this is possible. We have forwarded your ticket to our level 2 agents and as soon as we get some feedback from them we will contact you immediately. 

Hello Shriram,

We just got the feedback from our colleagues and they have told us that you can try and use this workaround, add this JS hook on the page where booking form is placed:

<script>
window.ameliaActions = {
  
  InitiateCheckout: function (success = null, error = null, data) {
    //triggered once the customer lands on the "info" page where they fill in //their details
    console.log('InitiateCheckout HOOK')
    console.log(data)
    console.log('------------')
// you can set value of the custom field here 
//(e.g. document.cookie, window.location.search - with some logic for parsing UTM)
    data.booking.customFields[2].value = "test" 
  },
}
</script>

and you can use custom CSS to hide that custom fields.

Hope this helps. 

Hello Shriram,

You are most welcome hopefully this will help you.

We wish you all the best.

Have a nice day.