Could the surname GREAG have been spelled GREIG... at one time or another?
I am searching WILLIAM-GREIG of Cook Islands [progenitor from Scotland] and your Samoan grandmother 'Siila' Laisa Lilio/Ilio GREAG came to my mind.
There is a GREAG/GREIG with a middle name of Lilo - coincidental? When I find the data I will save it this time.
In the meantime... what are your thoughts?