John Hartley is Abijah's only son, so surely he has to be Clifford's father.

1.  Marriage Record:

2.  1880 Census Every-Name-Index/Images (online at Ancestry.com):  John H. CHAPMAN (æ 5, b. MO) is living in Silver Creek Twp., Randolph Co., MO, with his parents (q.v.).

3.  1890 Census:  the 1890 Census Population Schedules were destroyed.

4a.  1900 Census Every-Name-Index/Images (online at Ancestry.com):  can't find John.

4b.  1900 Census Every-Name-Index/Images (online at Ancestry.com, Image #12-13 of 19):  214 Tecumsa West, Ottawa (Ward 4), Franklin Co., KS, Roll T623_489, pp. 276B-277A, SN 5-6, SD 86, ED 88, enumerated 6 Jun 1900, official enumeration date 1 Jun 1900 (extracted by Diana Gale Matthiesen):-

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

19

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27

*

214

124/119

127/128

Chapman Abija

Head

W

M

May 1825

75

M

50

PA

PA

PA

Stone Mason

3

Y

Y

Y

R

H

_______ Nancy

Wife

W

F

May 1832

68

M

50

9

5

VA

VA

VA

Y

Y

Y

_______ M????

D-in-Law

W

F

Oct 18??

??

M

0

1

1

KS

NY

OH

Y

Y

Y

[next page]

*

_______ Clifford

GSon

W

M

Mar 1900

3/12

S

KS

MO

KS

Y

Y

Y

*Tecumsa West

The page is water-damaged and partly unreadable (the page image at Genealogy.com is somewhat better than the one at Ancestry.com); this extraction is my best effort.  Abija is indexed "Gorga Ah," and Clifford's mother is indexed "Minnie Ah" — really.

5a.  1910 Census Every-Name-Index/Images (online at Ancestry.com):  can't find John.

5b.  1910 Census Every-Name-Index/Images (online at Ancestry.com, Image #9 of 14):  Third Avenue, Garnett City (Ward 1), Anderson Co., KS, Roll T624_431, p. 77A, SN 5A, SD 2, ED 21, enumerated 20 Apr 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):-

1910:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	13	14	17	18	19	20	23	24	25	26	28
118	122	Chapman A W	Head	M	W	88	M1	58			PA	US	US	Eng	Contractor	Cement	Emp	Y	Y		R	H
		_______ Nancy L	Wife	F	W	77	M1	58	9	5	VA	VA	VA	Eng	None			Y	Y
		_______ Clifford H	GSon	M	W	10	S				KS	MO	KS	Eng	None			Y	Y	Y

6a.  1915 Kansas State Census Every-Name-Index/Images (online at Ancestry.com):  John not found.

6b.  1915 Kansas State Census Every-Name-Index/Images (online at Ancestry.com, Image #158-160 of 650):  205 Cedar [St.], Ottawa, Frankllin Co., KS, Roll KS1915-90, p. 81, official enumeration date 1 Mar 1915 (extracted by Diana Gale Matthiesen):-

1915:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	4	5	6	7	8	9	10	11	15	19
O	F	564	593	L M Kelly 205 Cedar	42	F	W	IL	IL		50
				A W Chapman	92	M	"	VA	MO
				Clifford "	15	M	"	KS	KS	a

7.  1920 Census Every-Name-Index/Images (online at Ancestry.com, Image #3 of 18):  205 South Cedar Street, Ottawa City (Ward 2), Franklin Co., KS, Roll T625_532, p. 110A, SN 2A, SD 2, ED 93, enumerated 9 Jan 1920, official enumeration date 1 Jan 1920 (extracted by Diana Gale Matthiesen):-

1920:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

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2

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5

6

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8

9

10

11

12

17

18

19

21

23

25

26

27

28

*

205

34

43

Kelley Lola

head

O

F

M

W

48

wd

Y

Y

IL

PA

VA

Y

nurse

homes

W

Chapman Clifford

adopted son

M

W

19

S

Y

Y

KS

MO

KS

Y

Clerk

Drug Store

W

_______ Hartley

brother

M

W

39

wd

Y

Y

MO

PA

VA

Y

Contractor

cement

OA

Thomas Alice

sister

F

W

59

wd

Y

Y

IN

PA

VA

Y

nurse

homes

W

Chapman Abijah

father

M

W

98

wd

Y

Y

PA

PA

VA

Y

none

*South Ceader Street (sic)

It's odd that Lola adopted Clifford while Hartley was still living.

8.  1930 Census Every-Name-Index/Images (online at Ancestry.com):  John not found; Clifford not found.

9.  OneWorldTree (online at Ancestry.com):  a file there has him born 4 Mar 1876.