Instead of buying oranges, father bought mangoes. <-- is this sentence correct? or should it be Father?

Answer 1

It should be Father, because it replaces the name.

Instead of buying oranges, my father bought mangoes. <- is correct

Answer 2

If the sentence is speaking of your father and this is your proper name when referring to him, then it should be Father. If you were only indicating that your father bought mangoes, then the sentence should read, "my father..."

Answer 3

It should be capitalized if he was a priest, if you are replacing his name with Father, or if that's what's on his birth Certificate. If you say my father, then it is lower case.