There are a few quirks with the site. However, I have found a work around that will satisfy everyone.

You have the option of one King Bed or two Double Beds. You can choose how many adults and children. Just not off the first linked page.

Please follow these tips to make it work right for your needs. I also added these instructions on the amsat.org Symposium page.

73...bruce

Instructions for booking your room. Firefox blocked several of the features on this page. Try Internet Explorer or Edge, they worked fine. First, click on the link or copy/paste. You will be presented with one option... a King Bed with one person. Next, choose the dates for your stay. After that, click on Check Availability. This will allow you to choose either one King bed or two Double beds. After choosing the beds, click on Edit that appears under your check in and out dates and below the number of rooms and guests. You can change the number of adults and children in the room and make any other changes you need.