This is a group of characters and they have a group entry, but they also have a character entry and both are used - the former in the text and the latter to list them as the children of Apollo. I spoke to Greg about it and initially it was assumed to be a mistake, but it seems that both are used because there's currently no obvious way of linking genealogically to groups.

Edit: Greg has written new code so that groups may now be listed as having a genealogical connection to a character.