How to have multiple people complete form?

How can I have a form completed by multiple people before submission

If I understood you correctly you want that one submission contain data from multiple users. To archive this you will need to create approval workflow inside of your form. Basically you would need to provide you users edit link of submissions, so that each of them can update submission. 

You can check the steps provided by my colleague here: http://www.jotform.com/answers/401633#401648, to see how can this be done.

You can also search for some other methods into our support forum: http://www.jotform.com/answers/search.php?search=approval+workflow. 

If I did not understood your question correctly, please explain in more details what you are trying to achieve. 

Hope this will help. Let us know if you need further assistance.