How to allow multiple updates to a single InfoPath form(SP 2007)

Question

We have an infopath form with multiple sections eg: Section A is filled by Group A and Section B is filled by Group B .Both the Sections A and B are in the same form(SP 2007 and InfoPath 2007)

In order  to implement multiple updates by multiple Groups  we  automatically “Checked Out” the form  to that person

The issue Basically, when one person opens the  Form, it is automatically “Checked Out” to that person. Unless that person explicitly clicks the “Close”  button on the page, they will continue to be checked in. This locks out other people from making edits to the FORM, unless  the Admin team  manually checks out the person. Usually, people view the  FORM first but do not make any action upon it, and thus clicks the “X” for their browser to close. They are still checked in. 

We have 5 sections, 50 users all trying to update the Form