I've been researching the Merryman family in Cumberland, Co. Va and have some information that mightinterest you if you have not already found it.A William N Merryman was one of 5 or 6 sons of Jesse Merryman and Ann Tabb.William married Judith Brown. His name appears on Cumberland court records until 1807.He sold some property in 1804 that Judith was given by her father.
Incidentally, I think the Smyth Merryman you refer to is really Syntha (or Cynthia), one of the five daughters of Jesse.I've seen this spelling in several wills and deeds of this period and we know that Jesse had a daughter Cynthia who married a Thompson.
I'll be happy to exchange information with any Merryman researchers.I still have many unanswered questions. Clara