Portuguese Citizenship?

Hi everyone!

My dad’s parents were both born in Goa and immigrated to Canada. My grandpa passed away, but my grandma is still alive, born in 1940. My dad was born in India (not Goa) in 1962, they immigrated when he was just a child.

Are my parents and I able to apply for Portuguese citizenship based on this? What documents would my grandma need to have? Would dual citizenship be possible; Or do you have to choose one or the other?