Baby Girl Rapp was the daughter of John Rapp and Anna (Boston) Rapp.

As per her mother's obituary, seven children were living at the time of Anna's death in 1940: Mrs. Elizabeth Weber, Mrs. Mary Holzhauer, Edward Rapp, George Rapp, Fred Rapp, William Rapp and Henry Rapp, and five children were deceased: Otto in 1934, Louis in 1939, and three children in infancy. We know two infants are Johann and Carl. The third infant is a girl per her sister Elizabeth's obituary in 1945: Elizabeth was preceded in death by her parents, four brothers (Louis, Otto, Johann and Carl) and one unnamed sister in infancy.

As far as I know, there are no records of the date Girl Rapp was born and died, but I will keep looking. She was probably born on the Rapp family farm in Livingston County, Illinois. No burial information is available to my knowledge, but I am assigning her to the family plot at St. Petri. I am making a guess that since she was not given a name, she was stillborn or died shortly after birth. I think she may have been born between George (b. Mar 1886) and Johann (b. Oct 1889) due to the age gap, but she might have been born between Elizabeth (b. Dec 1892) and Mary ( b. Sep 1895) as there is an age gap there also.

The 1900 U.S. Federal Census states that her mother, Anna, had 11 children, and 8 were living. So three died before 1900.
The 1910 U.S. Federal Census states that her mother, Anna, had 11 children (should be 12 because Henry was born in Aug 1900 after the census was completed in April) and 9 were living. Three were deceased.

Siblings were:
Louis Christian Rapp (1882-1939)
Edward Rapp (1883-1956)
Otto Carl Rapp (1885-1934)
George Henry Rapp (1886-1950)
Johann Rapp (1889-1891)
Carl Friedrich Rapp (1891-1894)
Elizabeth Caroline Rapp Weber (1892-1945)
Mary Magdalena Rapp Holzhauer (1895-1985)
Frederick William Rapp (1897-1971)
William Daniel Rapp (1898-1992)
Henry S. Rapp (1900-1974)