It appears Isabella may have been fibbing about her age later in life because she is in the 1820-25 age class in the 1830 and 1840 censuses.  Maria Ann was not mentioned in her father's biographical sketch (see Sources below).

1.  John T. Humphrey.  1997.  Pennsylvania Births, Berks County, 1710-1780.  Humphrey Publ., Washington, DC (1998, Broderbund CD-196):

Child: Hanne Straup; Birth/Baptism Date: 22 Aug 1793;  Location: First Reformed Church, Reading; County: Berks;  State: Pennsylvania;  Father: Valentin Straup;  Mother: Mrs. Elizabeth Straup.

2.  Census Index:  U.S. Selected Counties, 1810 (Broderbund CD-313):  no Jacob SCHILLING/SHILLING found, at all, nor any SCHILLING/SHILLING in Berks Co., PA.

3.  1820 Census Index and Digital Images (online at Ancestry.com; Image #4 of 12; extracted by Diana Gale Matthiesen):

1820

PA

Berks Co.

Cumru Twp.

p. 5B

Jacob Shilling

100010-10100-0-000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	9 or under	1810-1820	= Levi (b. 1816)
1 male	26-44	1775-1794	= Jacob (b. 1796)
1 female	9 or under	1810-1820	= Hettie (b. 1818)
1 female	16-25	1794-1804	= Hanne (b. 1793)

Listed one line below Hanne's parents, Valentine & Elizabeth (RHEIM) STRAUB. 

4.  1830 Census Index and Digital Images (online at Ancestry.com; Image #11 of 32; extracted by Diana Gale Matthiesen):

1830

PA

Berks Co.

Cumru Twp.

p. 484

Ln. 4

Jacob Schilling

012 111 - 121 001

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	5-9	1820-1825	= Ephraim (b. 1821)
2 males	10-14	1815-1820	= Samuel (b. 1820) = Levi (b. 1816)
1 male	15-19	1810-1815	= ?
1 male	20-29	1800-1810	= ?
1 male	30-39	1790-1800	= Jacob (b. 1796)
1 female	4 or under	1825-1830	= Isabella (b. 1827/8)
2 females	5-9	1820-1825	= Maria Ann = Mary Louisa
1 female	10-14	1815-1820	= Hettie (b. 1818)
1 female	30-39	1790-1800	= Hanne (b. 1793)

The males born 1800-1815 did not appear in the 1820 census, so could not be sons of our subjects.  One of the daughters appears to have been fibbing about her age later in life.  They could be other kin or hired help.  Listed three lines above Hanne's widowed mother, Elizabeth (REIHM) STRAUB. 

5.  1840 Census Index and Digital Images (online at Ancestry.com; Image #30 of 33; extracted by Diana Gale Matthiesen):

1840

PA

Berks Co.

Cumru Twp.

p. 377B

Jacob Shilling

011 210 100 - 011 200 100

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
1 male	5-9	1830-1835	= Jacob (b. ca. 1832)
1 male	10-14	1825-1830	= ?
2 males	15-19	1820-1825	= Ephraim (b. 1821) = Samuel (b. 1820)
1 male	20-29	1810-1820	= Levi (b. 1816)
1 male	40-49	1790-1800	= Jacob (b. 1796)
1 female	5-9	1830-1835	= Elizabeth
1 female	10-14	1825-1830	= Isabella (b. 1827/8)
2 females	15-19	1820-1825	= Maria Ann = Mary Louisa
1 female	40-49	1790-1800	= Hanne (b. 1793)

There was no male born 1825-30 in the 1830 census, so this male would appear not to be their son.  Listed one line above Hanne's widowed mother, Elizabeth (REIHM) STRAUB. 

6.  1850 Census Index/Images (online at Ancestry.com; Image #53 of 73):  Reading, Spruce Ward, Berks Co., PA, p. 358A, 451/434, enumerated 9 Aug 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

Hannah Shelling	55	F				Cumru Berks Cty
Levi Shilling	29	M		Laborer		ditto
Louisa ditto	21	F				do
Isabella do	19	F				do
Jacob V  do	13	M				do

7.  1860 Census Images (online at Ancestry.com; Image #22 of 101):  Reading P.O., City of Reading, Spruce Ward, Berks Co., PA, p. 959, PN 253, 1875/1977, enumerated 10 Jul 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Hannah Shilling	50	F				100	Pennsylvania
Levi       "	30	M		Day Labourer			Do	Insane
Jacob V.   "	21	M		Boat Builder			Do
Isabella   "	23	F					Do

Listed six households from Hannah's brother, Christian STRAUB. 

8.  1870 Census Images (online at Ancestry.com; Image #56 of 67):  Reading P.O., Cumru Twp., Berks Co., PA, p. 210B, PN 56, enumerated 26 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):

400	407	Schilling Samuel	51	M	W	Farmer	20000	1400	Pennsylvania
		[Samuel's wife and children]
		_________ Levi	53	M	W				"	Insane
	408	_________ Hannah	76	F	W	Widow			"
		_________ Isabella	42	F	W	House Keeper			"

Living next door to Hannah's son, Ephraim.

9.  Morton L. Montgomery.  1909.  Historical and Biographical Annals of Berks County, Pennsylvania.  J.H. Beers & Co., Chicago.  On pp. 684-685:

JOHN JACOB SHILLING (deceased) founded a family in Berks County now well known there.  He was born in Chester County, Pa., and came to Berks County when a young man, settling at what is now Shillington.  He owned considerable land there, built numerous dwellings, and for many years owned and conducted the "Three Mile House," where he lived with his family.  He was a man of prominence in his day, and was of striking appearance, being erect, tall, and weighing over two hundred pounds.  He was a member of the Reformed Church.  He married Hannah Straub, whose father was Christian (?) Straub, and to them were born children as follows:  Levi died unmarried when about seventy years of age; Hettie also died unmarried; Samuel, who laid out Shillington and gave it its name ... [see Samuel's page]; Ephraim is mentioned below; Jacob, who was killed in the Civil war, married Mary Bechtel and had one child, who died young; Eliza married Isaac Miller, of Illinois, in which State both died; Isabella died unmarried; Louisa married a Forbs, of Minnesota... Ephraim Shilling, son of John Jacob, was born Nov. 16, 1822, in Shillington, and lived to his seventy-seventh year, dying Jan. 18, 1899.  There he spent his entire life.  He not only followed farming, but also his trade of pattern making, and turned out many violins of sweet tone; in later years he also engaged in wheel-weighting in connection with farming, cultivating a tract of forty-two acres.  In politics, he was a Republican.  In 1848 Ephraim Shilling married Catharine Marks, daughter of George Marks, and a family of eight children was born to them, namely: Clara m. Frank Welde; Catharine m. Julius Wagner; Elizabeth m. John Gauss; John Jacob m. Sarah Steffey, and (second) Sallie E. Berstler; Alexander E., unmarried, lives at Shillington; Hannah m. Jerome Tompkins; Jane m. Horace R. Carl; Andrew m. Lizzie Kane.  The family was Lutheran in religion.

Christian STRAUB was Hannah's brother; her father was Valentine STRAUB.

10.  Greg Lasley.  Descendants of Hans Adam Shilling (online at Lasley Family Genealogy).

11.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).