I'm not sure what "little plus sign on the side bar" means. I've just used the character menu to add a new character that consists of several characters and props AND which I don't want at least one of the characters to conform with another. An example might be troops in formation. I could group four soldiers into a single "character" so that I could either add rows or columns as needed. I have also exported a character group (person plus clothes) as a prop (3DS or Obj) and reimported the character as a prop. It puts less strain on the application and improves render time.

Gordon