I did study Shen Sha too, and yes the connection to Jie Sha that RapaNui discovered is interesting. With this Shen Sha, EB Mao has Jie Sha in Shen. And EB Shen has Jie Sha in Si. EB = Earthly Branch.
In Mangpai, it works differently. Mao has Jue in Shen, and Shen has Jue in Mao. It's vice versa.