<?php

$data[] = [
            'sponsor_id' => 2,
            'enroller_id' => 4,
            ];
//using [] after $data will concatenate otherwise override
$data[] = [
            'sponsor_id4' => 2,
            'enroller_id5' => 4,
            ];

//Following above there are two arrays in one array


print_r($data);
echo "<br />";echo "<br />";echo "<br />";
//To make it one array - so that new values add as an index
$data3 = [
            'sponsor_id' => 2,
            'enroller_id' => 4,
            ];
$my_array1 = array("sponsor_id2" => 4 );
$my_array2 = array("enroller_id3" => 5);

$res = array_merge($data3, $my_array2, $my_array1);

print_r($res);

?>