I found a copy of Hildegard and Abraham's marriage record which I'm attaching. It gives Hildegard's birth year as approximately 1939 and her parent's as Walter Schoene and Elsie Teeger. Hildegard was living in Elliot Lake, Algoma County, Ontario at the time of their marriage.
It then appears that she and Abraham settled in Elliot Lake. I found them on the 1972 Voter's List living at 246 Hillside Drive S, Elliot Lake.https://search.ancestry.com/cgi-bin/sse.dll?ti=0&indiv=t...
I then checked the telephone directory and there is still a Bishop living at that address. I will send you the full address and phone number in a private message.
I so hope this helps you find your birth mother.
Best of luck!