Hi there @vylla001,

Thanks for sharing with the Community.

Quick question, are these Klaviyo forms that you are utilizing or are you using custom forms? 

Klaviyo forms, unfortunately, cannot have custom code applied to them. What you can is create a custom legacy form that will allow you to add custom code to your forms. This also might have to be behavior that is looked at for your entire website. 

In order for you to successfully install a Klaviyo form on a Wordpress site, first, you will need to manually add the Klaviyo JS to your main theme file. Reference (it's for Shopify but it's the same script).
Typically, you should see a footer.php located under Appearance tab > Editor. That's where you would add the klaviyo.js script. You then create a form that will only appear on the URL for your page and have it add to a separate list you have for the page subscribers.

However, if you want to use Klaviyo forms I’d recommend looking through this community post:

and respective HC articles to set that up as well.

Thanks,

Alex