In 1900, Frank Allen (b. April 1876 IN) is living in Stanton, Dunn Co, WI with his Aunt & Uncle:
Henry Mosesb. Apr 1857 IN, parents born in Indiana Mary C. Mosesb. Man 1860 OH, parents born in Germany married 15 years Frank Mosesb. May 1888 IN Irvin Mosesb. Dec 1890 IN Maggie Mosesb. Apr 1897 IN Frank Allenb. Apr 1876 IN NEPHEW.
Angeline Platt's parents are listed in some census records as from Germany so I believe that Mary C. Moses is Angeline's sister.