I think we are close to connecting these families, too.If I understand your message correctly, David Gibb Sr. married Mary Elizabeth Gibbs -- almost the same last name except for the "s."Is this correct?Mary is the daughter of William Gibbs.
The Hamilton connection is as follows -- My ancestor David Hamilton Sr. (1775-1850s) married Mary Gibbs around 1800.My research has found reference to Mary being the daughter of William Gibbs -- a soldier in the Revolutionary War.I have no hard proof of her father's name or of his service.In the 1850 US Census for Neville Island, Allegheny County, PA several children of your David Gibb Jr and Margaret Gibb are living David (Sr) and Mary Hamilton or members of their families (James Dickson, etc...).I too have much information on the descendents of your David Gibb Jr.I inherited much of this research from my distant cousin Gladys Phillips (dec'd) who spent decades researching the Hamilton and Gibb families.
In the 1920s one member of our familiy working on the Hamilton genealogy advocated that Mary Hamilton was married to a Gibb before she married David around 1800.If we were to believe this, that could possibly make your David Gibb Jr. the son of Mary.I have found no primary evidence of this connection.
There indeed must be a family connect between my David and Mary Gibbs Hamilton and your David (Jr) and Margaret Gibb, because of the Gibb children that were taken in following the death of the parents.I am referring to the 1850 census.
Did David Gibb Jr. leave a will when he died in 1842?
Sylvia, you can e-mail me directly at firstname.lastname@example.org.I have my genealogy records at home and will pull the Gibb materials back out tonight.
Look forward to working with you to possibly solve this mystery.