Barb, I believe you are correct with a birthdate of 1735 for Shadrack Casteel. I have several sources merged with some discrepancies. The will of Edmund III Casteel lists his children: Lucy Casteel b: 1733 Shadrack Casteel b: 1735 Machack Casteel b: ABT 1740 in Prince George's Co, MD Susannah Casteel b: 1743 in Prince George's Co, MD Abendego Casteel b: ABT 1747 in Prince George's Co, MD Edward Casteel b: ABT 1750 in Prince George's Co, MD Francis Casteel b: ABT 1752 in Prince George's Co, MD Cassindra Casteel b: 08 JAN 1753 in Prince George's Co, MD Charity Casteel b: ABT 1757 in Prince George's Co, MD Kezia Casteel b: ABT 1758 in Prince George's Co, MD Sarah Casteel b: ABT 1762 in Prince George's Co, MD
I regret that I have nothing on the Tubs family, but it appears there may some connection between a Roberts family and this line of the Athy/Athey family.
1.Owen Athy's sister, Mary Fenley Athy b.Oct. 30, 1744 Prince George's Co., MD was married to an unknown Roberts. 2.Owen's Brother, Elijah Athy b.Abt. 1720 PGC MD, had a grandson, Robert Palmer Athey b. April 23, 1801, Prince William, Virginia who was married to Mary Polly Roberts b. 1811 OH daughter of Abraham Roberts and Anna Catherine Delawder. They were married in Ohio and eventually migrated to Illinois.
Speculation: From the census birthdate (1790), and location (PA), you mention of Louisa A., it seems possible she may be the Loiza Casteel b. June 16, 1790, Bedford Co., PA the daughter of Zadock and Sarah (Athy) Casteel, who was married? to an unknown Athey. I would conclude from the 1850 census information that William A. Roberts, Sr. and his wife Delia (Casteel) Roberts, had Delia's widowed/divorced or unmarried mother, Louisa/Loiza (Casteel) Athey living with them as well as widowed grandmother Sarah (Athy) Casteel.