Yes, they are sisters. They admitted to Luke Ford recently that they have had incestuous relations off the porn camera.

http://lukeisback.com/bloglukeisback/?p=601

http://www.xxxporntalk.com//ubbthreads/showflat.php?Cat=&Board=monkeycage&Number=245327&page=0&view=collapsed&sb=5&o=&fpart=1