Hello, Meghan!
My, you sure have a fun group trip to Walt Disney World planned for next June!
What you are looking for is information about
Disney's Rider Swap option, which is "available at select attractions in all 4 Disney Theme Parks."
You and the other adults (and your 7-year old, too, if he's tall enough and wants to ride) will be able to ride the ride, then "swap" with another set of you, making sure that someone is there to watch the little ones without having to wait in line two separate times.
As stated on Disney's webpage, just ask a Cast Member at the attraction who will help explain how this works once you're there. This is a great way for everyone to enjoy as much of the parks as possible, so go and have fun!
Send more questions as you think of them! We love to help!