72 hours VISA free valid for Hong Kong to Toronto Via Shanghai

I am going to Hong Kong from Toronto and like to stop over Shanghai on my to Hong Kong or on my way back to Toronto.
Based on what I read here, I think I have eligible for the 144 hours free transit with my Canadian Passport. I plan only to tour Shanghai within that 144 hours.
I will have confirmed tickets from different airlines instead of a single ticket showing the stop over. I think Air Canada, for example, does not do flights between Hong Kong and Shanghai. Am I still eligible for the free stay with tickets from different Airlines ? Does it make any difference between doing that on my way to Hong Kong from on my way back ?