All of the Lenster soldiers on the east side of the map (You can tell they are Lenster, they suck and have Javelins) must either be left alive or captured and released. The Green Knights and their children must also survive to get the Member card.
An ideal strategy to do this is to open the eastern door and have a disarmed unit block the door. The Knights will all move in that direction, and you can pick off the couple of fake ones with arrows or magic. Meanwhile open the west door and capture the children. Now, slowly have someone with good avoid lure each Knight over to the west side of the map one by one. Release their respective child when you know they are not in Xaviers range and they will escape via the west exit. This is a surefire, good way to make sure that they all escape. Don't walk in Xaviers range or let the children run wild, as they will be killed by him.
EDIT: There is an image of who goes with who in my guide, but its not in the correct format.
