You can 'Pitch In' by contributing, or providing a helping hand. When user receives an Invitation, they will see a section with event details, and a section with list of items (shown below).
To Pitch In, click Yes to RSVP, click 'Count Me In' Button to contribute, then submit response.
To provide a Helping Hand, expand the Helping Hands Panel, Click the 'Count Me In' button, and submit response
If more than one person is helping with an item, you may click the name dropdown to see who else is participating.
If you would like to make a change, click the name drop down, remove name, make required change, and resubmit response
This feature allows you to make changes or remove your name, if needed. Note, to access invitation again, click 'View Invitation' button on Invitation Email that was sent to you.