I am using the jQuery validate plugin (available here:  https://jqueryvalidation.org/) and it is working as expected.

Now i want to add another input field to the form, but it is outside the <form> tag. I am using the HTML 5 attribute "form" to indicate it is part of the existing 

more info here: <form>  https://www.impressivewebs.com/html5-form-attribute/

example: <input type="text" class="form-control" name="x" form="originalForm">

Can anyone tell if it's possible, and how i can include those fields in my validation?

Kind regards,

Sander