I now know which of my ancestor's sister married Jehudah Ashmun/Ashman. Her name was Mabel Bristol, b. in Woodbury, CT.
Sounds as if the name had particular significance in the Ashmun/Ashman family -- maybe above and beyond the one who went to Liberia (I found him after I posted my initial query).
Apparently Jehudah died. She was a widow with two children when she married Zebulon Stoddard (according to someone on the Stoddard forum). They lived in Westport, Essex County, NY. But that's about all I've been able to find out.
I would still like to know the names of Jehudah's parents, where they were married, when he died, the names of the Ashmun children, etc. Hope someone has this information.