Move VAT field after billing Last Name (or any other field I want)

Hello,
How can I move the plugin VAT field to show after one of the billing fields?

I’ve already set up in functions.php a function that orders all my Billing Fields

At some point I have all the priorities set up and they works fine.

I would like to show your plugin content after this very field:

$checkout_fields['billing']['billing_last_name']['priority'] = 9;

How can I do this?

Thank you!