You probably know most or all of this, but the story of Samuel Elliott (1748-1831) and Mary Richardson (1760-95) is in John Woolf Jordan’s Colonial families of Phila vol 2 p 1636-9;
An abstract of the will of Samuel’s father, John Elliott, describes Samuel as “in Anne Arundel Co Md.” and mentions land and slaves there. (p 22-3 in “Abstracts of Phila County Wills 1790-1802” on the internet).
The marriage of Samuel Elliott and Mary Richardson on Sept 16, 1780 is in “Marriage Record Exchange 1777-1850…100 Marriage Records from Ann Arundel Co., Md.”, in “Daughters of the American Revolution Magazine, vol 43-5, p 613 (on the internet).
The 1790 census for Anne Arundel Co Maryland lists Samuel Eliott, 2 males over 16, one under 16, 4 females and 7 slaves. This is on p 363; his presumed father-in-law, Richard Richardson, is on p 360. The 1800 census for Philadelphia, Walnut Wd, has Saml Elliott, 2 boys 0-10, himself over 45, one girl 0-10, and three girls 10-16. In the 1810 census he is in Chestnut Wd, next door to John Elliott Cresson, with one boy 10-16, himself over 45, and three young women 16 to 26. In the 1820 census, Lower DE ward, he is over 45 with one female 16-26 and three 26-45. I don’t have access to the 1830 census.
In the 1793 Phila. Directory Samuel Elliott is listed as a currier at 93 South Front St. His brother John is a looking-glass maker and medicinal merchant at 60 South Front St. (Joseph Richardson, silversmith, and his brother, Nathaniel, ironmonger, are nearby at 50 South Front St, and Joseph was a witness to John Elliott Sr’s will, but this family seems not to be related to Samuel’s in-laws.) (http://www.archive.org/stream/philadelphiadire1793phil#page/120/mode/2up/search/richard)
John and Samuel Elliott owned a glassworks on Market Street between 2nd and 3rd Streets from 1772 to ’80.Their partner was Isaac Gray, a wine merchant who had married their sister, Mary Elliott. (“Report on the manufacture of glass” J D Weeks, p 80 on the internet, and http://www.manheim1762.org/files/A_brief_history_of_the_Philadelphia_Glass_Works_.pdfhttp://www.manheim1762.org/files/A_brief_history_of_the_Philadelphia_Glass_Works_.pdf) Mary Gray’s 1797 will mentions her deceased husband and her brothers. (p 170 in “Abstr of Phila Co Wills 1790-1802.)
There were land transactions in 1775 and ’79 involving Isaac Gray, John Elliott, his wife Annabelle, and Samuel Elliott in Hampshire County Virginia (now West Virginia) on the Potomac River south of Bedford County PA.(“Early Records, Hampshire County, VA”, C M Sage, L S Jones, pp 15, 23 on the internet)