Gives good explanation of cross/line/inbreeding http://www.poultry.allotment.org.uk/Poultry/Start_Keeping_Bantams/bantam_chicken.php
This has a good chart for line breeding http://journeytoforever.org/farm_library/ppp/ppp6.html
You can breed mother/son and fathers/daughters just no full brother/sisters. I think you can brother/sister only if there is an unrelated(different mothers or father)