I am working on a theory that the Popp family in Manning and my Grau family in Manning are blood related through the Sachleben family back in Germany.
Below is the information that shows John Popp marrying Anna Sachleben, and Detlef Grau marrying Sophia Sachleben.
A couple of big clues are that this picture below came from the Popp lady in Montana, and in my cousin's Grau information it states that the couple in this picture were attendants at the marriage of Anna Grau and John Meister in Lake View.
Then the Jentzen source found that Detlef Popp was a farm hand for Carl & Lena Grau in Lake View, with Lake View being another common denominator.
I have contacted a 6th cousin, who is a Sachleben and he has more detailed information on this family, and hopefully he will be able to make the Sachleben connections.

Amos & Anna (Popp) Epsen
Information from a Jentzen descendant
Detlef Carl Lawrence Popp (1861-1914) who married Frederika Jentzen, immigrated from Germany in 1880, single, age 19, travelling with his mother, Anna Popp, age 57. In the 1885 Iowa State Census for Carroll County, Washington Township, Iowa, Detlef Popp was living in the Carl Detlef & Lena Grau household, as a farmhand, single, age 23, born in Germany.
Detlef Popp’s parents were born in Germany, according to his 1888 marriage record in Carroll County: John L. Popp & Anna M. Sachleben

Information from Dave Kusel's Grau cousin
Carl Detlef Grau (son of Detlef & Sophia (Sachleben) Grau) was born on September 1, 1858, in Grossenaspe, Neuminster, Schleswig Holstein, Germany, and was baptized on October 3, 1858.
His Godparents were Carl Louis, Claus Sachleben and Gottlieb Grau. He came to America with his parents in 1869 at the age of 11 years.
They settled in Davenport, Iowa, Clinton County, and later moved to Wheatland, Iowa, where they lived for five years.
The family then moved to Westside, Iowa, in Carroll County, to a farm seven miles northwest of Westside where he grew to manhood.

Carl married Magdalena Moller on November 5, 1880. Magdalena was born on February 9, 1859, in Schleswig Holstein, Germany.
She came to the U.S. with her parents. After their marriage Carl and Magdalena farmed 6 miles south east of Arcadia, Iowa, where they lived for 19 years.
In 1900 they moved to Lake View, Iowa, in Washington Township, Carroll County, making their home in town for five years.
They then moved to a farm one mile west of town and lived there for six years and then returned to Lake View where they had purchased a home.
First child of Carl & Magdalena - Anna Sophia Grau was born on May 9, 1891, in Carroll County, near Arcadia. Anna had a child, Carl, at the age of only 14. She was married on October 30, 1907, in Sac City, Iowa, at the age of 16 to Mark Cox from Lake View, Iowa. Both of her parents had to give their written approval because of her age. Mark was a farmer and they were later divorced.
Anna was married to John Meister on November 30, 1911, at the Congregational Parsonage in Lake View, Iowa. They were attended by Miss Anna Popp and Mr. Amos Epsen.

Detlef Jacob Grau - TWIN of Gottleib Johann Grau, was born on July 27, 1833, in Bad Bramstedt, Schleswig Holstein, Germany. Detlef, being the oldest of the twins, was named after his father. Detlef and Gottlieb were christened on August 2, 1833 at Evangelisch Kirche (Protestant Church) in Schleswig Holstein. Detlef's Godparents were Jacob Reimer, Johann Bremer, and Anne Boge. He married Sophia Margaretha Sachleben of the village of Grossenaspe (6 miles northeast of Bad Bramstedt) on November 26, 1854. Sophia was born on September 20, 1832, to Claus Friedrick and Magdelena (Pieper) Sachleben in Schleswig Holstein, Germany. (Documents pertaining to Detlef: Marriage Letter and Proclamations Document from Gerber in Bramstedt, November 26, 1854, Pox Vaccination Paper from Henning, September 21, 1837, and Poorman's Certificate from Steckmest in Bramstedt, September 4, 1854.) After their marriage Detlef and Sophia lived in the Bad Bramstedt area until April 15, 1869, when Detlef, his wife and five children came to America. Both Detlef Jacob and Sophia Margaretha are buried in the Manning City Cemetery. Detlef and Sophia had nine children, seven of the nine children preceded their father in death: Anna Magdalena, August Frederick, Julius Carl Christian, Johann Wilhelm, Emma, Otto and Grover Herman, five of those seven died from the black diphtheria plague. Survivors were: Carl Detlef of Lake View, Iowa, and Claus Heinrich (Henry) of Manning, Iowa.

So if anyone in either the Popp or Grau families can help with the Sachleben mystery - Please e-mail Dave Kusel