Hi Lynn, yes 'frustrating' is one of the first words that can be used with the Campbell/Gay line coming from Calfpasture VA! I am both a Campbell and a Gay but only a Time Machine could help me find out exactly who they all were and how on earth they were all related!
I descend from William Campbell and Sarah Gay...everyone on the net has Sarah Gay being born 27 years BEFORE her suggested Mother, Margaret Lockridge, the wife of Robert Gay.
I do see in "The Chronicles" v. III, pg 297 where it appears that William Campbell and wife Sarah Gay gave to Thomas Gillham 200 acres on the Calfpasture in 1751.
Now, Thomas Gillham, Sr. married Margaret Campbell the daughter of William Campbell and Sarah Gay.
This land deed would suggest therefore that Robert Gay and wife Margaret (Lockridge) were Sarah Gay-Campbell's parents and the grandparents then of Margaret Campbell-Gillham. BUT if so, then the dates all over the net, as you suggest, have been 'adjusted' to fit the necessary massaging to make a group of children FIT. frustrating indeed!