Forms Version 11.0.2311.50556

We have a publicly available process in LFForms that our website provider has hosted within an iFrame on our page.  The form works great.

But they have requested that I use a thank you page they have set-up instead of the usual built-in thank you functionality that I use on most forms.

I've configured the "Message Start Event" so that "On Event Completion" it uses the "Redirect to website" option to go to the thank you page they have set-up.  That works, but now that are getting upset that it opens the page within the iFrame and they are wanting me to set the form submission to include a target="_PARENT" option.

I've told them that we can't do that the way they want, that we can only redirect to the URL and can't control the target like that - but I wanted to confirm that is in fact correct.

Is there a way to set the redirect to target="_PARENT" on form submission or am I correct that it isn't possible?

Thank you!