app/controllers/frontend/checkout.php
add
$cart_products = fn_sort_array_by_key($cart_products, 'company_id');
after this line
$cart_products = array_reverse($cart_products, true);
(!) Not tested
app/controllers/frontend/checkout.php
add
$cart_products = fn_sort_array_by_key($cart_products, 'company_id');
after this line
$cart_products = array_reverse($cart_products, true);
(!) Not tested