Multi-part Join Form
I would suggest you try out Caldera Forms CiviCRM WordPress plugin: https://github.com/mecachisenros/caldera-forms-civicrm

You need to firstly install the Caldera Forms plug-in for WordPress and then install the Caldera Forms CiviCRM plug-in (also for WordPress). Caldera Forms out of the box, allows for the creation of multiple pages for a single form. The Caldera Forms CiviCRM plug-in, adds the integration with Caldera Forms and CiviCRM. I currently have both plug-ins installed in our WordPress site and I'm busy exploring the creating of a contact capture form with custom CiviCRM fields. The form is pretty large, so I am busy splitting it into multiple pages. I have not tested any form submission yet, but hope to complete the form and test it within the next week.