Are you sure you want to tackle this puzzle? What follows are only the best conclusions I have made to date, not FACTS. After working on this, Louise Selby in 1963 wrote

I hope that I shall never see another Selby family tree,
A tree whose many pages blessed with long-lost kin and those at rest,
A tree that looks toward God to say there're many Selbys here today,
A tree among whose branches bare, there was someone who didn't care,
Some who thought the venture just a lark, and some who didn't leave a mark.
This tree's researched by fools like me and recorded now as history.

{Definition of history: Myth agreed upon.}

James Wilson SELBY (ca. 1747, Pr. Geo. Co., MD - ca. 1821, Adair Co., KY) m. by 1778, Elizabeth ( ), wid/o Wm. BENNETT. James & bro. Samuel inherited "Fatt Oxen," Fredk. Co., MD, from father Wm. Magruder SELBY. The first controversy is the interpretation of the 1776 Census: St. John's & St. George's Parishes, Pr. Geo. Co., MD. These are not consecutive but are nearby entries, pp. 126 & 127 of published (typewritten) census.

Zachariah JENKINS [males] 50, 18, 20, 14, 9, 6, 4, 2; with Martha [females] 28, 14, 11, 22, 1.
Sarah LANHAM 41, 17, 6; son 6.
Elisha HOSKINS, 28.
Joseph PRATHER 46, 16, Ruth 46.
Wm. M. SELBEY 67; Martha 63, 16.
Wm. W. SELBEY 47, 31, 14, 12, 4, 2; Elizabeth 30, 17, 9, 6.
Nathan SELBEY 41, 8, 5; Agnes 28, 2.
Joshua SELBEY 35; Sarah 35, 11.
James SELBEY 29, 25; Ruth 23, 1. [Some say that Jas. first m. Ruth, but I think that Josiah, 25, & wf. Ruth, 23, were living with James in 1776.]
Lingan 23, 1; Drucilla 20 [SELBY, but surname not given].
Jeremiah FOWLER 65, 27, 21, 17, 13, 10; Drucilla 53,38,16,7.
Isaac FOWLER 33, 12, 6; Elizabeth 28, 7, 1.
Thomas FOWLER 30, 21; females 3, 3, 1.
Archibald LANHAM 25, 1; Jane 27, 1.

In the household of Wm. W. SELB(E)Y in 1776, which man was 47 & which was 31? That was not likely to be a son only sixteen years younger. Could Wm. W. have been head of the household including his brother 31 & a 30-yr-old wife of the brother? To complicate matters further, the 17 is difficult to read for the female aged 17, & some have said it was 27 (I don't think so.) In the James SELBY household, who were 29 & 25? [I think James 29, bro. Josiah, 25.]

William Magruder SELBY (ca. 1709 [67 in 1776]- 1783) was s/o William SELBY & Sarah MAGRUDER. His will was pr. 21 Jan. 1783. He m. ca. 1734, Martha WILSON, b. ca. 1713 [63 in '76], d/o Josiah WILSON & Martha LINGAN. Wm. M. & Martha had

William Wilson SELBY (ca. 1729? - )m1. _? m2. Martha ( ) (28 in 1776), wid/o Zachariah JENKINS.
Samuel (14 Feb. 1733/4 [bpt. record] - 1830, Union District, SC [obit]), m. Anny.
Thomas, d. Russell Creek, Green/Adair Co., KY, m. Rebecca LEVINS. In 1787, Post Vincennes, IN, inhabitants incl. Thomas S(H)ELBY under heading of men, with Joshuah, Jos-h, & Wm. SELBY as boys. He gave POA to Richard LEVINS of Bullitt Co., KY, to sell land in Washington Co., PA, "Thomas LEVEN's Old Place."
Nathan [41 in 1776], m. Agnes HOSKINSON [28 in '76].
Joshua Wilson [35 in 1776].
James Wilson SELBY, b. ca. 1747 [29 in 1776]
Josiah Wilson, m. Ruth, d/o John HOSKINSON. [Was he 25, with James?]
Lingan Wilson SELBY (ca. 1753 [23 in 1776] - 1821, Green Co., KY) m. Drucilla FOWLER, d/o Jeremiah.
Martha Wilson SELBY m. BENNETT.
Sarah, m. BAKER.
Eliz., m. Nicholas LEAVENS.
Mary, m. 25 F 1783, Nicholas NAYLOR.

Will of Wm. Magruder SELBY, Pr. Geo., MD, T:1:165, 28 F 1773, 21 Jan. 1783. To wf. Martha, coexx. with son Wm. W. To sons Wm. Wilson SELBY "Grub(by) Thicket." To sons Samuel & James Wilson SELBY. To sons Nathan SELBY, Joshuway Wilson SELBY, & Josiah Wilson SELBY "Chew's Folly," To son Thomas Selby & daus. Martha, Sarah, Elizabeth, & Mary. Wit: Wm. WILSON, Jas. BEALL, Jeremiah FOWLER.

James Wilson SELBY & Elizabeth ( ) BENNETT had

Sarah, b. Dec. 1779, Pr. Geo. Co., MD m. bond, 5 F 1798, KY, James NAYLOR (Mar. 1771 - 17 July 1834/5, Adair Co., KY).
(Wm.) Joshua, b. ca. 1780, m. 1807, Milly ORME/ORIN.
James, b. ca. 1782, m. [another controversy, Jane ORME &/or Lucy STAPP?]
Elizabeth, b. 178_; m. 25 Aug. 1808, Adair Co. KY (John) Walter ORME.
Greenbury (1786/7 - 1851, Russell Co., KY) m. 3 Je. 1813, Elizabeth CONOVER.
Rachel, b. ca. 1788, m. 23 Dec. 1806, Adair Co., KY, Jas. McDANIEL.
Mary/Polly, b. ca. 1790, m. 28 July 1808, Adair Co., KY, Thomas LOCKE.
Simeon, b. ca. 1795, m. Elizabeth MORRIS.
Drusilla (10 Apr. 179[5?] - 7 Je. 1884) m. 15 Apr. 1816, Johnson PARHAM (21 S 1794 - bef. 1 Mar. 184[6?]), Bledsoe Co., TN, Probate K:210. [killed 5 May 1846?]
Lloyd SELBY (5 Oct. 179[6/8?]- 9 Oct. 1880)?

Tollett Cem., on Bledsoe/Cumb. Co. Line, TN, has Simeon SELBY, d. 23 July 1876. [1850 Census, b. ca. 1795], next to
Elizabeth [MORRIS] SELBY (24 Mar or May 1815 - 18 May 1872).
Lloyd (5 Oct. 1798 - 9 Oct. 1880) m. Rebecca PARHAM.

Cumberland Co., TN, A:405; Bk. G:375, Simeon SELBY, dsp, heirs: (James) Loyd SELBY
Green B./Greenberry & [his son?] Levi/Levy SELBY
Elizabeth, wf/o Wm. WELLS.
Catherine, wf/o Isaac WELLS, Russell Co., KY, A:405.
Annie M. & Selly THOMAS, Adair Co., KY.
Eliz. ORME, Van B., AR.
Alex NAYLOR (s/o Sarah SELBY & Jas. NAYLOR)
Jas. CALHAN/CALHOUN & wf. Eliz (NAYLOR)
Anderson MURRELL & wf. Lavenia (NAYLOR)
Susan MURRELL. (Susanna NAYLOR m. Jesse MURRELL? Kitty m. Nich. MURRELL)
Samuel, Sarah, Eliz. A., & Jas. K. CRAVENS.
Lydia MARTIN
James SELBY
Elizabeth WELLS (Eliz. SELBY, b. 1823, m. Wm. WELLS. Catherine SELBY m2. Isaac WELLS.)
Franklin & Sarah J. DARNELL.

Drucilla PARHAM et al v. Polly LOCK, et al, I:79: Drucilla sold her interest in 1879; Loyd & Rebecca received one- tenth share. Sarah & Jesse SHERRILL, K:119, 125, 126. Walter L. SELBY of Jackson Co., AL, 1882, A:496.
Book A, 496, 1882, Walter L. SELBY, Jackson Co., AL, claims share of estate of Simeon SELBY.

Crossville Times, 23 Jan. 1888, Petition to sell land, filed by E. G. TOLLETT, admr., Green B. SELBY, v.
Tempy SELBY, wid/o decd.
Sarah, formerly SELBY, SHERRILL of White Co., TN.
Heirs of Nathan SELBY, nonresidents of TN.
Walton/Walter SELBY, nonres.
Eliz. (SELBY) SHERRILL
Katy/Kitty (SELBY) KEARLEY.
Wm. KEARLEY of Rhea Co., TN, & Sarah KEARLEY of Bledsoe Co.
Heirs, if any, of Linda/Lina (SELBY) HAN[D[COCK.

Bledsoe Co., TN, Census of 1850:
550. Simeon SELBY, 55, KY; Elizabeth, 34, TN; & Lucy MORRIS, 58, NC. [Lucy = mother of Eliz.]
552. Samuel KERLEY, 22, TN: Catherine, 26, AL; Joshua, 3, TN; Daniel, 1, TN; KY; Rebecca, 56, GA; Wm., 24, TN; Eliz. J., 21, TN.
562. Loyd SELVY, 53, KY; Rebecca, 56, GA; Wm., 24, TN. Eliz. J., 21, TN. [Loyd (5 Oct. 179_ - 9 Oct. 1880, Cumb. Co.,TN, s/o Jas. W.]
563. John B. MORRIS, 37, GA; Mary, 35, TN; Martha J., 1, TN; G. B. SELBY, 37, KY.
564. Shamuel SELBY, 26, TN; Elizabeth, 24, TN; James L., 4, TN; Daniel, 1, TN.
676. Simeon SELBY, 28, AL; Rebecca J., 33, TN; Sarah, 7; Milly, 4; Mary C., 3, & Loyd 6/12, all b. TN. Crossville Chronicle: L. S. SELBY d. 19 Je. 1930, aged 80, in Algood (west of Crossville) b. 30 N 1849, Sequatche Valley (south of Crossville) m. 14 Jan. 18[86?], Sarah BENNETT.

These may help sort out the names: James W. SELBY had Greenberry, b. ca. 1786/7. Greenberry, b. 1829. David had a Green, b. 1846. Levi had James Green, b. 1843. Levi & Mary Cath. had Simeon "Simms," b. ca. 1848, Russell Co., KY, d. TX; m. Eliz. McKINLEY.

Well, now you know where some of the SELBY family were. Let me know when you have this line all proven. :-)