Help with update after insert

Goal: After inserting into a table (VOLUNTEERS), I would like to update a field in a table it references (PFA_EVENT_DETAIL).

Issue: In the update portion below, I do not know how to get it to update the referenced/parent row in PFA_EVENT_DETAIL.

export function submit_click(submitEvent) { 
 if (!$w('#txtFirstName').valid ||
        !$w('#txtLastName').valid ||
        !$w('#txtEmail').valid ||
        !$w('#nbrVolQuantity').valid ||
        !$w('#txtPhone').valid) {
         $w('#txtError').text = "One or more fields are not valid";
         $w('#txtError').show();
 return;
} //close function submit_click   

 var data = {
 "first_name": $w('#txtFirstName').value,
 'last_name': $w('#txtLastName').value,
 'title': $w('#txtEmail').value,
 'phone': $w('#txtPhone').value,
 'quantity':$w('#nbrVolQuantity').value,
 'comments':$w('#txtComments').value,
 'ped_title':eventDetailId, // This is "title" field which is referenced in VOLUNTEERS collection and the row I want to later update
  };

  console.log("ped_title:eventDetailId = ",eventDetailId); //sanity check.
 
  wixData.insert('PFA_VOLUNTEERS', data).
    then( (results) => {
            results.fulfilled = results.fulfilled + 1;
            console.log("insert results ",results);

          wixData.update('PFA_EVENT_DETAIL', results).
            then(() => {
              console.log("UPDATE results ",results);
            });

        $w('#txtError').hide();
        $w('#txtSuccess').show();
        $w("#txtFirstName").value = null; 
        $w("#txtLastName").value = null;
        $w('#txtEmail').value = null;
        $w('#txtPhone').value = null;
        $w('#nbrVolQuantity').value = null;
        $w('#txtComments').value = null;

}); 

}

This clearly doesn’t work because it’s looking for the PK of the VOLUNTEERS table to update in PFA_EVENT_DETAIL. I want to have it update the row associated with the bold column from the log:


insert VOLUNTEER results  
{...}
first_name: "Some"
last_name: "One"
title: "me@mail.com"
phone: "5555551212"
quantity: 1
comments: ""
ped_title: "f5a179c4-035f-41b1-98dd-85c20eb34f2e" - want to update fulfilled column for this id in PFA_EVENT_DETAIL
_id: "c13d6cb9-ac64-4ae8-9349-26e95da6421c"
_owner: "c58a35bd-3657-401d-a3e5-a663cb09307a"
_createdDate: "2019-08-14T18:41:11.594Z"
_updatedDate: "2019-08-14T18:41:11.594Z"
fulfilled: NULL

Item [c13d6cb9-ac64-4ae8-9349-26e95da6421c] does not exist in collection [PFA_EVENT_DETAIL].

Any help would be greatly appreciated. Thank you in advance.