A wordpress page is containing a contact form 7 receiving a url parameter. Works fine. (example.com/contact?product=TShirt will prepopulate contact form 7 field)
On the page with the contact form I added another selection on top of the page, lets say 'size'. I like to read the existing parameter (product), add the new parameter (size), form a link like ?product=TShirt&size=XL#anchor.
Currently, I link ?size=XL#anchor which makes me lose the existing parameter.
example.com/contact#anchor?product=TShirt&size=XL
?