You can book on behalf of some Gather invitees, here's how.
Gather allows you to book on behalf Travelers who have RSVPed "Yes" to your meeting in Gather but haven't yet booked. (Note that if they haven't RSVPed, you're currently unable to book for them.)
Note that you may need to know where your traveler is coming from, when they want to travel, their date of birth, gender, secure traveler information and loyalty numbers (if they're not stored in AmTrav already), and a card for their travel (if you're not providing one for them) in order to book on their behalf.
Step 1: Navigate to Invites under See in your lefthand navigation bar.
Step 2: Find the relevant invite for your traveler under Team Invites (note that you can search for the meeting name or traveler name) and click View on the righthand side:
Step 3: Select Book Flight (or Book Hotel, or Book Car Rental -- whatever's offered) to proceed to their travel search:
Step 4: Note that the meeting name is noted at the top of the page throughout the search, from here you can proceed with the search to book on their behalf (more instructions on booking are here).