This might help - hopefully? It's all in Polish I'm afraid, but the link is to a site grouping the Dajczak families from the area of Olejów, Podole. You can click on the family trees to enlarge them. Maybe some names will ring a bell?
Are your grandparents still alive? Are they willing or not not to talk about where they grew up in Poland before emmigrating to Canada? My grandparents never talked about where they grew up in Poland or even that there was family still living there. I had to use clues to learn where they were born and what part of Poland these towns are in. So for example, did your grandparents ever write to anyone in Poland? The address might give a clue as to where to start. If the writer or the family are still alive as well, they may be able give you help. So, start by checking with the family first by asking for letters and documents.
My name is also dajczak, I noticed you are trying to find out more about the family name
that my father jozef Dajczak lived in a place Brody Podkamien ( Below the monestary), my father was sent to Siberia and the joined with general Anders and fought with him Italy, Monte Cassino as part of the polish II Corps . He remained in the UK in exile, as many who returned were killed (Murdered) . I was born in the UK but still keen to know more about Poland and my fathers history , I also know that the name Sikora is also connected to my family, my father did say that we had relatives in Canada, he used to write to them when he was alive