Son said to be, but cannot be:
.  Henry CUPP, b. 1855
Henry cannot be their son because Sarah was 53 or 54 years old in 1855.  Sarah stopped having children in 1845, which is biologically reasonable.

1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):  not found.

2.  1840 Census Index and Digital Images (online at Ancestry.com; Image #21 of 25 — indexed as "Capp"; extracted by Diana Gale Matthiesen):¤•

1840

OH

Fairfield Co.

Bloom Twp.

p. 423B

Ln. 22

Capp/Cupp Daniel

100 001 - 220 000 100

0000000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	4 or under	1835-1840	= Philip (b. 1838)
1 male	30-39	1800-1810	= Daniel (b. 1809/10)
2 females	4 or under	1835-1840	= Daughter A = Mahala (b. 1835/6)
2 females	5-9	1830-1835	= Sarah (b. 1833/4/5) = Caroline (b. 1832/3)
1 female	40-49	1790-1800	= Sarah

The second letter of the surname is barely more than a blob; it could be CAPP or CUPP.  The list is roughly alphabetized, so no neighborhood reconstruction is possible.

3.  1850 Census Index/Images (online at Ancestry.com; Image #7 of 16):  Bloom Twp., Wood Co., OH, p. 140A/279, 478/499, enumerated 24 Aug 1850 (extracted by Diana Gale Matthiesen):¤•

Daniel Cup	40	M	Farmer	100	Ohio
Sarah	48	F			"
Caroline	17	F			"
Sarah J	16	F			"
Mahala	14	F			"
Philip	12	M			"
Elizabeth	10	F			"
Mary A	8	F			"
William	5	M			"

4.  1860 Census Images (online at Ancestry.com; Image #30 of 31):  Woodberry P.O., Bloom Twp., Wood Co., OH, p. 308A, PN 185, 1366/1349, enumerated 11 Aug 1860 (extracted by Diana Gale Matthiesen):¤•

Daniel Cupp	50	M		Farmer	800	400	O
Sarah	50	F					"
Phillip	22	M		Labor			"
Caroline	27	F					"
Mary	18	F					"
Charles	16	M					"
Henry	5	M					"
Sarah	24	F					"

Sarah is too old to be Henry's mother.  Note that Henry is not with them in 1870, so either he died or he went to live with some other kin.  But why is the younger Sarah listed last?

5.  1870 Census Images (online at Ancestry.com; Image #24 of 64):  Eaton Rapids P.O., Eaton Rapids Twp., Eaton Co., MI, p. 199B, PN 24, 206/203, enumerated 1 Aug 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):

Cupp Daniel	61	M	W	Farmer	1600	400	Ohio
____ Sarah	68	F	W	Keeping House			Ohio
____ William	25	M	W	Farm Laborer			Ohio

Living two households from their daughter, Sarah Ann (CUPP) MILBOURN, and 12 households from daughter, Caroline (CUPP) GOODWIN.