Question 1: Why does Mason not want Antoinette to call Sandi "my cousin Sandi""

-"I knew who he was, his name was Sandi, Alexander Cosway's son. Once I would have said `my cousin Sandi' but Mr Mason's lectures ad me shy about my coloured relatives. I muttered, `Thanks you'" (Rhys 50)

Mason is known as a person that looks down at the blacks, and dismisses them as inferior, so he is not proud of his black roots. By Antoinette calling Sandi "my cousin Sandi", she forms a bond with him that Mason does not approve of. Why Mason cares so much about what Antoinette, though, remains vague. It is highly likely that it is part of his scheme (mentioned below).

Question 2: Why is Antoinette's name only mentioned towards the end of Part 1"

-"The new nun wiped my eyes with a large handkerchief, gave it to...