Thank you for the dates and your help.The dates all seem to be in the 1770s except the death date found in a genealogy with no record.
I did some further reading and searching at the library online site I mentioned earlier.The Book of Agnew by Mary Virginia Agnew does mention Samuel being from South Carolina but I did also find a book written in 1892 by Jedediah Adams on the life of David Hayes Agnew.In his book he claims to have gone to original sources, one source being the unpublished genealogy recorded by James and Rebecca's grandson Smith, son of David. Adams concluded from those records he saw that there were three Agnew brothers who migrated to America one who was unnamed, Samuel and James. He mentions specifically that James' brother, Samuel, settled in South Carolina, and James in Lancaster co. and the third brother in New Jersey.Mary Virginia Agnew also mentions a brother of James named Samuel but her book is not organized well which is confusing.In one place she said Samuel's stone was at Marsh Creek.Others say it is James stone that is there.But she does put Samuel Agnew as James son living in South Carolina and quotes her source as a descendent, Samuel Agnew from Mississippi.
The Daughters of the American Revolution patriot list mentions Samuel of South Carolina as the patriot and adds a notation that records of earlier ancestors were submitted but not verified.James the son of James and Rebecca is listed as a patriot.There were three by the name of James Agnew and one of them required further proof for membership. There was also a George from South Carolina. I could find no Agnews in the RW Recordsonline but do not believe that project was ever completed.
I will add that the proof of Rebecca Scott being an aunt and not a sister to Hugh Scott is in the will records of Lancaster co.Those abstracts are online also.