I have been doing a little more research on this, and found Dominic in the 1880 census, living with the Behrs family.
1880 Lake, Cook, Illinoispg. 218 John Behrs46 (Born: Germ) Carpenter Elizabeth Behrs44 (Born: Germ) Joseph Behrs18 (Born:Ill) Lizzie Behrs17 (Born:Ill) Lena Behrs12 (Born:Ill) Charles Behrs2 (Born:Ill) Dominick Engleman 21 (Born:Germ) Brakeman
Unless Therese was a cousen of these Behrs, the only one that makes sence is Lizzy (Lena is possible, but would have had to marry very young). Perhaps Therese was Lizzy's saint name (From what I understand a lot of German Catholics include the family patron saint in their names. This can sometimes get confusing when reading official records.)