I have a regular drupal 7 form (based on a content type called guests) where I need a "Bring my partner" checkbox. When the checkbox is clicked, a field collection field (first name/last name/address) needs to be prefilled basing on the details for the currently logged-in user. (Partner details are in my user account details.)
Can this be done in
hook_form_alter()? Is there any other way to achieve this?