@davmerit I did, along with https://www.ads-software.com/plugins/contact-form-7-modules/ but the only possibility is capturing the $_POST variable. I had some variables stored in my $_SESSION and for that there is no solution.
What I’ve done now is I created a hidden field with Contact Form 7 and with an AJAX request to my server I got my $_SESSION variables (they don’t contain private data so that’s no problem). After the Ajax call I stored them in the value of the hidden field.
I’m aware it’s not the best solution as it’s a bit of a workaround, but it looked like the easiest way to do it..