Sakura Gari
you can try this one. it's father x son pairing.
http://www.mangago.me/read-manga/eien_ni_owaranai/
Lost child
You should search for Ogawa Chise she 's drawn some really dark ,incest yaoi like Ibitsuna kakera ,Ienai Itami o Daite Iru both are one shots but in the same series
Inheritance of the aroma
Nanadome No Gomenne
Could someone help me find some yaoi with incest, especially dark ones.