In the 1910 Greenville, Hunt, TX census, Luther and Inez had a son, Howard R. then 6.
On 14 Feb 1973, Howard Randolph DUCK died in Denison, Grayson, TX, age 69. His wife Letha, was the informant on his death cert and she said that Howard's father was Luther DUCK and his mother's maiden name was Inez HURNI.
In the 1900 census in Union, DeKalb, IN, living with the Akin LODEWICK family is Inez HURNI, 18, OH Switzerland OH. Her relationship says help, probably as a domestic or nanny.
There is a Samuel HURNI family in the 1880 Milford, Defiance, OH census: self, Samuel, 36, Germany Ger Ger, farmer wife, Eliza J., 24, OH OH OH, keeps house son, Ertis, 8, IN dau, Cora E., 6, IN son, Alford, 4, IN son, Frederick, 1, IN bro, Andrew, 14, IN Ger Ger, farm laborer
I'm not sure where this family is in 1900 except Alford may be in Reeves Co. TX as HERNE.
PS. Milford Township is in the northwest corner of Defiance county adjacent to DeKalb Co. IN.