As an administrator, you are all powerful. Well, our lawyers say we have to add a disclaimer. You probably still can't leap tall buildings in a single bound. But you can edit a sign up participant's slot. Dare to dream big, right?
Log into your account and click Tools, located on the left side of your account Sign Ups page. Click Edit People on Sign Ups. Select the sign up and click the OK button. Click the pencil icon to the right of the person's name to get to the edit screen where you can make changes. You can also choose to send an email notification directly to the group member. Remember to check Save before moving to the next step.
If you are working with an RSVP sign up, choose the Edit option next to the group member's name in the slot you wish to change. From the edit screen, you can change the name, edit the response to the RSVP and edit any items that the person signed up for as well. Check the box to send a notification directly to this group member. Select Update RSVP to save any changes.
See? Nothing can stop you now! Except Kryptonite. We'd still recommend staying away from that stuff.