Hi Bill:
It looks like you have extensively research the Cavey line in Howard County. Your missive didn't state that it included Baltimore County, but I am assuming that it does as the Cavey family moved back and forth between the two. I would like to throw a few Cavey names at you to see if they tie into your family line.

Henry Cavey b.~1806 or 1812 (depending upon which census)
m Sarah (?) b.~1808
Nathaniel* b~1820
Thomas b.~1825
William H b.~1832
John D b.~1836
Sarah A b.~1838
Joseph B b.~1839
Zachariah b.~1847
Mary E b.~1851
Margaret b.~1855

*May not be their son - Sarah's age would be 12 when he was born - could be younger brother of Henry.

John D. Cavey (son of Henry)
m Mary (?) b.~1845
as of 1870 Census - known children:
William b.~1866
Kate b.~1868

I believe William (son of John) is the same William H Cavey found on the 1900 abd 1920 census in Baltimore Co.

Family as follows:

William H Cavy b.3/1866
m Lizzie M Clark b.2/1868
Pearl b. 5/1894
Florence b. 7/1892 m Herbet Clarke
Emma b. 2/1894
Cecelia b.7/1900 m Andrew Webb
James b. 1904
Ida b. 1905
Stanley b. 1906
Vernon b. 1909

William and Mary were married about 1888/9 - there are also three unknown children born to the couple before 1900 but as they are not listed on the 1900 census I surmised they were dead. William is listed as living on Christian Ave in Baltimore in 1890.

Dates and location links the families together, but I was wondering if you have anything in your records that confirm my "hunch." I also believe that Joseph and Henry were brothers. Any ideas on who their father might be?