Not only would you be related to the Coffman Family through your ancestor Eliza Ann Coffman, but also all Lomans who are decedents of Isaac B. Loman and Phoebe Davenport are related to some Coffmans. Phoebe married Leonard Franklin Coffman after Isaac died. She and Leonard had at least one child, Leonard Franklin Coffman, Jr. so all of Phoebe's Loman children had a half brother who was a Coffman. So, for your line John W. Loman and his wife, Eliza A. Coffman, had a mutual half brother. Hope this isn't too confusing. Leonard Franklin Coffman, Jr. raised his family in the Jefferson Co. IL area and some of his descendents still live in that area.
I do have a large Loman file which would not post well on this forum. I also have a file on the decedents of Leonard Franklin Coffman, Jr. I can e-mail these files to you if you send your e-mail address directly to me at firstname.lastname@example.org