I think I found Abington on the National Registry homes in Maryland.It is on the internet.See follow up posted to Larry's message.
Regarding Brice and Cassandra Gaither.I now have Harry Wright Newman's book "Anne Arundel Gentry".The name Brice is listed on several pages.pps. 81,85,87,98, 110,114,115,117,118,339.They are not all the same Brice.I didn't look up all references, but found that their parents were Edward and Eleanor Reid. Edward (1714-1777) was the son of Benjamin and Sarah (Burgess) Gaither. (Same line that I am from through Edward's brother, Henry).Eleanor seems to have been the Widow Whittle when she married Edward. All the following information is from this book. I can't say if it is all accurate.
After Edward died Eleanor is said to have gone to North Carolina with her sons, and I assume daughters.Eleanor and Edward had 12 children.Brice was the 8th child and Cassandra was the 11th. Cassandra may have been quite young when her father died.Surely her mother wouldn't have left her behind.
According to Edward's will Cassandra was unmarried when his will was written March 26, 1777.Eleanor died May 4, 1792 in N.C. and then Cassandra m. James Reid Nov. 8, 1792.
Newman states that Brice m. Elizabeth, the daughter of Alexander Reid.He lived in North Carolina for a while then went to Georgia.Eatonton, PutnamCounty..