Katy,
If your ancestor lived in Schilling, you will need to email Gary Martens who has a database of the Lower Volga Villages which includes his work on census and church records. See email here: https://www.schillinggr.org/database.html As you've discovered Schilling is also known as Konstantinovka (Volga village), but there is also a daughter colony Konstantinovka (https://volga.domains.unf.edu/colonies/konstantinovka). It was founded in 1859 from those who were in Schilling, Jost, and other colonies. The Ehoff family also lived in the village of Jost. Gary may be able to find more information for you from family lists. Given Peter Ehoff's second wife's name as Filbert, it is unlikely they were Black Sea Germans (now Ukraine), so that could be ruled out (I also checked data there). Peter most likely married Amalia in Konstantinovka.
You can also become a member of AHSGR.org and receive a discount on purchased records to complete your family tree. Because families moved from one village to another you have to trace them using census and any church records (most not available online). Some volunteer coordinators have them for their village and each village is different, thus the emails to VCs and purchase of records is often necessary.
The Filbert lines lived in Schilling, Beideck, Konstantinovka, and also Grimm and have German origins to: Gronau (Bensheim), Kr. Bergstraße, Hessen See Dr. Mai's research here: https://volga.domains.unf.edu/surnames/filbert
The Liverpool to Boston manifest shows he came with his brother Carl Ehoff and the scribe lists "cousin" H Ehof. If you have not already, fully research Carl as you may be able to find additional information.
Based on a quick search of my own, the Winnipeg to Vermont manifest lists his father as Heinrich in Konstantinowka and the family was bound to his brother Gottlieb in Fort Collins, CO (probably to labor at sugar beet factory there). See second page of manifest. Researching Gottlieb may also give you additional information on the parents. "Vermont, St. Albans Canadian Border Crossings, 1895-1954," database with images, FamilySearch (https://familysearch.org/ark:/61903/3:1:3QS7-9981-3SY1-L?cc=2185163&wc=3KMS-L2W%3A1018492201%2C1018499401 : 9 October 2015), (M1464) Manifests of Passengers Arriving in the St. Albans, VT, District through Canadian Pacific and Atlantic Ports, 1895-1954 > Roll 154, vol 144, May 1911 > image 643 of 752; citing NARA microfilm publications M1461, M1463, M1464, and M1465 (Washington, D.C.: National Archives and Records Administration, n.d.).
See also: "Vermont, St. Albans Canadian Border Crossings, 1895-1954," database with images, FamilySearch (https://familysearch.org/ark:/61903/3:1:3QS7-99DQ-2SXK-9?cc=2185163&wc=3KMC-3TG%3A1018494101%2C1018632301 : 9 October 2015), (M1461) Soundex Index to Canadian Border Entries through the St. Albans, Vermont, District, 1895-1924 > Roll 132, D650 Napoleon-E130 William > image 1040 of 5228; citing NARA microfilm publications M1461, M1463, M1464, and M1465 (Washington, D.C.: National Archives and Records Administration, n.d.).