Geri....Since you said Delphine and Adolph married in Benton County, Indiana, I looked at all the Alexander families in that county in 1880 and found this.Other census records, say Delphine's parents were born in Canada, so PERHAPS this is a POSSIBILITY for being her birth family???Do you happen to know the names of any of Delphine's siblings?This 1880 census is on www.familysearch.org:
NameRelation Marital Status Gender Race Age Birthplace Occupation Father's Birthplace Mother's Birthplace
Rufina ALEXANDERDauSFemaleW9INCANCAN (my note: think this MIGHT be Delphine??)
Source Information: Census Place York, Benton, Indiana Family History Library Film1254266 NA Film NumberT9-0266 Page Number249A
Don't know "if" William Alexander is Delphine's father, but this William was living in Newton County, Indiana on the 1900 and 1910 census records with lots of his children and was a widower.Here is a link to the Newton County Death Index.In the death records, there is a William Alexander who died in 1915.