Wow.. this is very interesting.
I am also a descendant of Greig. David Willam Greig is the name of my great-grandfather. He married a woman from Beru Island (one of the islands in Kiribati). Her name is Teniba. I think they have four daughters but I'm not sure. I only know two of them. Their names are Caroline and Helen. Helen David Greig is my grandmother. She is my mother's mother. My family are currently living in Christmas Island in Kiribati.
All thanks to your great-grandmother for I am beginning to know some part of the story of this great family. And did you know that Capt William Greig also had a son in Australia? I read the story in one of the groups created in Google.