A45-39 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
B-1821 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
Rus14-56 and Rus14-57 in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766.
Family #86 in the 1775 Grimm census.
Family #19 in the 1798 Grimm census.
Family #59 in the 1834 Grimm census.
Note: Jakob's father Heinrich Daniel Wolff is not listed in the 1775 Grimm census, but his sons Bernard and Jakob are. They are also the only two Wolffs listed as departing from Denmark in The Immigration of German Colonists to Denmark and Their Subsequent Emigration to Russia in the Years 1759-1766. Jakob Wolf is listed in family #86 in the 1775 Grimm census.
Note: German records spell the surname with two Fs, as in Wolff.
Jakob Wolf was the son of Heinrich Daniel Wolff and his wife Susanna Catharina Maria. He was probably born in Georgehausen, Hesse, Darmstadt, Germany, the same town as his father, around 1750. He was the second oldest of seven children. 
In 1759, Danish King Frederick V invited Germans from Hessen and the Palantinate to help settle the area of Schleswig-Holstein, at that time under the control of the Danes.  The king was interested in converting the marsh lands to arable farm land. Germans were known for their good farming skills and for being hard workers, so it seemed like a win-win situation both both Danes and Germans. Eager to provide a better life for his family, his father decided the opportunity to immigrate to Denmark was too attractive to pass up.
The Wolff family left for Denmark on 07 June 1762 from the Colony of Altona in Flensburg with a group led by Christoph Paquet.  They arrived in Flensburg, Duchy of Schleswig, on 12 June 1762.  They took their oath of allegiance to Denmark onn 19 July 1762 and were classified as reserve colonists.  In June of 1763 the family was living at Numbeer 4 Dehnen Hof in Colony F6 Friderichsheide in the region of Flensburg. 
The marshlands were very inhospitable to farmers. Although the Germans were good farmers with typical farm land, it was far more difficult to convert these former wetlands and grow crops. Most of the German immigrants barely reaped enough to feed their families, let alone to provide food for others in Denmark. When Catherine the Great invited Germans to immigrate to Russia, his father decided it offered him a better opportunity to provide for his family. In April of 1765 he applied for permission to leave Denmark and go to Russia.  That application was granted.
It is assumed that his father had every intention of leaving Denmark, but the Danish records that show which Germans went to each Volga colony do not include his name, only the names of his two oldest sons. It is unclear if he passed away in Denmark, remained in Denmark, or went to a different village. There is no notation of his death, and it seems unlikely that he would change his mind after getting approval to immigrate to Russia and stay behind in Denmark. Most likely his father passed away either in Denmark or in one of the Volga villages before the 1775 census was taken. If his mother Catharina Maria was still living, she may have remarried and lived with her new husband's family. It is possible that she may have passed away, but, again, there is no record or notation of her death in the existing records.
I've checked the census records for any and all Wolf family members. None of Bernhard's or Jacob's siblings lived with them at the time of the 1775 census. It seems most likely to me that either Heinrich Daniel and his wife stayed behind in Denmark with their younger children, or he passed away, she remarried and took her younger children to live with her in her "new" home, wherever that was.
1775 Grimm Census 
1798 Grimm Census 
1834 Grimm Census 
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