Ohio Marriages, 1800-1958, database, FamilySearch (https://familysearch.org/pal:/MM9.1.1/XDKV-BXQ : 10 February 2018), Joseph C Elliott and Catharine Miller, 04 Oct 1838; citing Preble,Ohio, reference ; FHL microfilm 0461073 IT 1-2.
Ohio, County Marriages, 1789-2013, database with images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/2QHJ-WN5 : 8 December 2014), Joseph C Elliott and Catharine Miller, 04 Oct 1838; citing Preble, Ohio, United States, reference ; county courthouses, Ohio; FHL microfilm 564,963. 
1850 United States Federal Census - Randolph, Illinois; Year: 1850; Census Place: Randolph, Illinois; Roll: M432_125; Page: 68B; Image: 389; Ancestry.com; Ancestry.com Operations, Inc.; 2009; Provo, UT, USA ; Ancestry image: 
United States Census, 1850 - Randolph county, Illinois, taken 26 September 1850, database with images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/M8P1-27F : 12 April 2016), Catharine Elliot in household of Joseph C Elliot, Randolph county, Randolph, Illinois, United States; citing family 1003, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).; FamilySearch image: ; image on WikiTree: 
United States Census, 1860 - Township 6 S Range 6 W, Randolph, Illinois, taken 1 August 1860, database with images, FamilySearch (https://familysearch.org/pal:/MM9.1.1/MXHD-B8D : 13 December 2017), Eve Miller in entry for Joseph Elliott, 1860.; FamilySearch image: ; image on WikiTree: 
It may be possible to confirm family relationships with Catherine by comparing test results with other carriers of her mitochondrial DNA.
However, there are no known mtDNA test-takers in her direct maternal line.
It is likely that these autosomal DNA test-takers will share DNA with Catherine: