

From Acestory.com, the following was listed under Brooklyn, NY Directories 1888-1890:

Great-great Grandfather, George Hierl. He was drafted into Company B, 81st Regiment of the New York Volunteer Infantry. His military records at the National Archives revealed that he served in Williamsburg, Virginia and was for a time stationed at Fort Monroe. Here are scanned images of 'badges' from his uniform.
* The maiden name Siebert was recorded in the National Archives pension file for George Hierl (alias Hill), although from the Diocese archives in Regensburg it appears that her maiden name was Seiz.
Johann and Magaretha, along with their children Georg and Barbara (Redig), came to America on the ship Elsfleth that left from Bremen and arrived in New York on 1 Nov 1853. It listed the family as: Hirl, Johann, 57, male, shoemaker, from Germany, to USA; Georg, 25, male, shoemaker, from Germany, to USA; Magaretha, 58, female, from Germany, to USA; Barbara, 18, female, from Germany, to USA. [From: "Germans to America" Volume 6 (Oct 1853 - May 1854) on page 13]*
* Found by my distant cousin Elaine Redig Meyer along with the following information she obtained from another relative who made a trip to Regensburg (Umelsdorf) and obtained from the Diocese records the following:
Marriage on 18 February 1822
Johann Hierl, shoemaker in Umelsdorf, born on 24 March 1796 in Umelsdorf, son of Georg Hierl and his wife Anna, maiden name Schmoll,
with
Margaretha Seiz, born on 26 February 1792, daughter of Johann Seiz, farmer in Ramersberg and his wife Margaretha, maiden name Stolz
Witnesses were the father of the bridegroom and Martin Langhanns, surgeon from Lengenfeld
Notes: Went to America in 1853
Stillbirth on 16 February 1823
Boy, stillborn, son of Johann Hierl, cobbler in Umelsdorf, and his wife Margaretha, n. Seiz
Baptism on 4 January 1824
Anna Margaretha Hierl, born on 4 January 1824, daughter of Johann Hierl, cobbler in Umelsdorf and his wife Margaretha, n. Seiz
Sponsor was Margaretha Fuchs, wife of blacksmith in Utzenhofen
Notes: Died on 29 May 1836
Baptism on 6 November 1825
Anna Hierl, born on 5 November 1825, daughter of Johann Hierl, cobbler in Umelsdorf and his wife Margaretha, n. Seiz
Sponsor was Anna Fuchs, wife of farmer in Eispertshofen
Notes: Died on 29 March 1831
Baptism on 19 May 1828
Georg Hierl, born on 19 May 1828, son of Johann Hierl, cobbler in Umelsdorf and his wife Margaretha, n. Seiz
Sponsor was Georg Fuchs, blacksmith in Utzenhofen
Notes: Went to America in 1853
Baptism on 8 September 1832
Johann Baptist Hierl, born on 7 September 1832, son of Johann Hierl, cobbler in Umelsdorf and his wife Margaretha, n. Seiz
Sponsor was Georg Fuchs, master blacksmith in Utzenhofen
Notes: Died on 22 September in the same year (i.e. 1832)
Baptism on 23 July 1835
Barbara Hierl, born on 23 July 1835 at 1 hour past noon, daughter of Johann Hierl, cobbler in Umelsdorf and his wife Margaretha, n. Seitz ? daughter from Ramersberg
Sponsor was Margaretha Fuchs, wife of blacksmith in Utzenhofen
Notes: Went to America in 1853
So Barbara & George were the only children who lived to adulthood and their parents came with them to the U.S. in 1853. Barbara's mother's maiden name was spelled Seitz one place and Seiz several places. I would assume Johann Hierl's baptism about 24 March 1796 was recorded in the same set of books, but I don't think they researched back any further than finding Barbara's parents.
Doing some follow-up, another cousin, Adrienne Noeker Pellegrino found the following:The marriage between Johann SEITZ (born Abt 1743 in Ramersberg, Parsberg, Bayern died 16 Dec 1819) and Margaritha (Margaretha) STOLZ (born Abt 1761 in Lengenfeld, Parsberg, Bayern died before 1795) resulted in the following children:
1. Johann SEITZ
born 11 Jun 1783 in Ramersberg, Parsberg, Bayern
died 1783
2. Johann Nepomuk SEITZ
born 06 Mar 1875 in Ramersberg, Parsberg, Bayern
died 1785
3. Margaritha SEITZ
born 01 Jan 1787 in Ramersberg, Parsberg, Bayern
4. Maria Walburga SEITZ
born 01 Feb 1788 in Ramersberg, Parsberg, Bayern
died 04 Feb 1788
5. Maria Margaretha SEITZ
born 26 Feb 1792 in Ramersberg, Parsberg, Bayern
However, Johann SEITZ (born Abt 1743 in Ramersberg, Parsberg, Bayern died 16 Dec 1819) also married a Barbara ?? (born Abt 1770 in Ramersberg, Parsberg, Bayern).
With Johann SEITZ (born Abt 1743 in Ramersberg, Parsberg, Bayern died 16 Dec 1819) information I was also able to obtain from the www.familysearch.org website his parents which were listed as Georg SEITZ (probably born approximately 1718) and Mrs. Barbara SEITZ (probably born approximately 1718). The website also listed Johann SEITZ (born Abt 1743 in Ramersberg, Parsberg, Bayern died 16 Dec 1819) as also being born in Unterbuchfeld, Parsberg, Bayern and died on 16 Dec 1819 in Unterbuchfeld, Parsberg, Bayern.
This information can be obtained from the International Genealogical Index on the following:
Film # 1239585, Ref # 3914
Film # 170765, Page # 1797
Film # 178018, Page # 758, Ref # 22827
Film # 1239633, Page # 555, Ref # 18694
Film # 1239633, Page # 555, Ref # 18685
It appears the family of SEIZ is also referred to as SEITZ.