Secondary sources give our subjects two sons, Johann George and George Michael.  If our subjects followed German naming practices, as it appears they were doing (with all sons having the same saint's name, in this case, Johann), then Johann George and George Michael are the same person, that is:  Johann George Michael KAPP, as I have shown above (which explains why nothing is known of George Michael).  It is not at all unusual for a German to have three (or even four) given names.

1.  F. Edward Wright.  1994.  Berks County Church Records of the 18th Century.  Vol. 4.  Family Line Publ., Westminster, MD (Broderbund CD-166).

SELECTED PASTORAL RECORDS OF JOHN CASPER STOEVER of baptisms and marriages performed in the general area of Berks County... Tulpehocken - Marriages... 1739... February 26 - Johann Friederich Kapp and Eva Maria Graff.

On the same list with (Joh.) Andreas KAPP and (Joh.) George Veitt KAPP.  John Casper STOEVER was Evangelical Lutheran; church was near Bernville, PA. 

2.  William Henry Egle, ed.  1890.  Names of Foreigners Who Took the Oath of Allegiance to the Province and State of Pennsylvania, 1727-1775, with the Foreign Arrivals, 1786-1808.  Pennsylvania Archives, Vol. XVII, Second Series, Harrisburg, PA (reprinted 1967ff by Genealogical Publ Co., Baltimore, MD; in 2000 as Broderbund CD-512):

p. 45	LIST OF PASSENGERS IMPORTED IN THE SHIP PENNSYLVANIA, JOHN STEDMAN, MASTER, FROM ROTTERDAM, LST FROM PLYMOUTH. QUALIFIED SEPT. 11, 1732... Michael Capp... Georg Friedrich Capp... Hans Georg Graff... — [The original list is herewith given.]...
p. 46	Hans Graff... Michael Capp... Frederick Capp...

3.  Israel Daniel Rupp.  1876.  Thirty Thousand Names of German, Swiss, Dutch, French, and Other Immigrants in Pennsylvania from 1727 to 1776.  (repub. 1931, Leipzig; republ. 1965, Genealogical Publ. Co., Baltimore, MD; Broderbund CD-267):

p. 073	20) Sept. 11, 1732. Palatines imported in the ship Pennsylvania, Jno. Stedman, Master, from Rotterdam, last from Plymouth.--Col Rec. III. 452. Seventy-three males above sixteen; women and children, of both sexes and different ages, ninety-eight--in all, one hundred and seventy-one.--(Editor.)
p. 074	Hans Georg Graff, ?... Michael Capp, Georg Friedrich Capp...
p. 465	APPENDIX No. XIV. NAMES OF EARLY SETTLERS IN TULPEHOCKEN, BERKS AND LEBANON COUNTIES. — As early as 1723, thirty-three families of Germans, who had come to New York 1710, settled in Schoharie 1713, left there and located on Tulpehocken Creek; among these were... In 1728, others from Schoharie settled here... Andreas Kapp...
p. 466	The first settlers in Tulpehocken were Lutherans and German Reformed.  Rev. Tobias Wagner was the first pastor of the Lutheran Congregation.  The following is a List of the members of the Tulpehocken Church, from 1743 to 1746: Georg Graf sen., Friederick Kapp, Andreas Kapp... Andreas Graf...
p. 467	Joh. Martin Cass, Geo. Vitus Cass, Joh. Michel Kapp... Johannes Graf... Georg Graf jr...

The big question is:  Is the Andrew KAPP who came to Tulpehocken in 1728 the same one who appears there in the 1740s?  The five KAPPs in Tulpehocken in the 1740s are considered to be brothers ("Cass" is obviously a misreading of "Cap"), who immigrated to Pennsylvania in the 1730s.  So if, as it seem probable, these are two different Andrew KAPPs, how does the one from New York relate, if at all, to the ones there in the 1740s?  And, in any case, how are we going to separate their children?!

.  Ralph Beaver Strassburger (William John Hinke, ed.).  1934. Pennsylvania German Pioneers: a Publication of the Original Lists of Arrivals in the Port of Philadelphia from 1727 to 1808.  2 vols.  Norristown, PA (reprinted 1966ff by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-267):

p. 66	[List 20A] A List of Palatine Passengers on Board the Ship Pensilvania Merchant, John Stedman, Commander, from Rotterdam. [Qualified Sept. 11, 1732.] MENS NAMES... Hans Graff...
p. 67	Michael Caap Fridrich Caap WOMEN AND CHILDREN...
p. 68	A true List. John Stedman.  73 Men  98 Women & Children ___ 171 [Total]   3 dead ----- 168 [Persons] Philadia Septemr 11th 1732. Present: The Honble Pat. Gordon, Esqr, Lt Govr, S. Hassell, Esqr, Mayr, A. Hamilton, Esqr, Recorder. The foregoing List was upon Oath declared by John Stedman to be a true & exact one. Robt Charles, Cl. Con. "At the Courthouse of Philadelphia, Septr 11th, 1732.... A List was presented of the Names of Seventy Palatines, who with their families, making in all One hundred & sixty eight Persons, were imported here in the Ship Pensylva. Merchant, John Stedman, Master, from Rotterdam, but last from Plymouth, as by Clearance thence." From the Minutes of the Provincial Council, printed in the Colonial Records, Vol. III, p. 452. [List 20 B] Palatines imported in the Ship Pensylvnia Mercht, of London, Jno Stedman, Mr, from Rottr, but last from Plymouth, p Clearance thence. Qualified Septemr 11th 1732...
p. 69	Hans Georg Graff... Michael Capp Georg Fridrich Capp... [List 20 C] Palatines imported in the Ship Pensylva Mercht, Jno Stedman, Mr.
p. 70	Hans Georg Graff... Michael Capp Georg Friedrich Capp... Philadia Sepr 11th 1732. At the Courtho in presence of the Govr, the Mayor and Recorder of the City, the foregoing Qualifications were taken &
p. 71	subscribed by the several foreigners whose Names are contained on this Leaf. Robt Charles, Cl. Con.

.  Land Records: Bucks and Lancaster Counties, Pennsylvania, 1682-1825 (Broderbund CD-652):

Record ID	Date	Residence	Book-Page	Remarks
41144	28 Mar 1748	Lancaster Co.	B-548	Deed
Property	400 acres in Heidleberg Township
Grantor	Widow Mandoline Groffe
Grantees	Andrew Groff, George Groffe, Hans Groffe, Sebastian Groffe, Leonard Holstein, Barbara Holstein, George Emort, Eva Maria Emort, Frederick Kapp, Eva Maria Kapp, Martin Kapp, Margaret Kapp
Grantee's Wife	Catherine Groffe

.  William Claude Buss.  KAPP Family Web Site: Descendants of Stephen KAPP. [link died]   Claims our subject is the son of Simon Peter KAPP.

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

.  Messages in the Kapp Family Genealogy Forum (online at GenForum.com).

.  Messages in the Cupp Family Genealogy Forum (online at GenForum.com).

.  GNIS:  Geographic Names Information Service (online at USGS.gov):  it's Stouchsburg (originally Stouch's Town), not Stouchburg nor Stouchberg.