hi Sarah, if they came to Canada in 1845, then it is highly likely they went through the quarantine station at Grosse Isle. There is actually a project dealing with that station, you might want to check them out. Add it to your tags on this question to draw their attention.
I have found this site https://registers.nli.ie/ and verified every baptismal records in every county of the McKinley clan and found my great uncle records with noted parents Patrick and Grace McKinley as parents (ggrandparents)
Note when Patrick Mckinley left Ireland, he moved to the Plantagenet area in Ontario Canada.
I am confident I will find other pieces to assemble the McKinley puzzle.
Thanks for your reply