I may be able to help. The Graham's,McAdams's,Ray's,McWilliams' and possibly came to America in the 1840's. The men established themselves first it seems in NY then moved as a group to Van Buren Co.,MI. mostly in the Decatur Township area. There was marriage between the Grahams & Rays (Reay in Ireland). Although they came during the potato famine years, that wasn't the reason they came. They came because of religious persecution. They were Presbyterian. This came from interviews with Gertrude (McAdams) Smith at age 104 and from Iva (McAdams) Lyle age 93.
I may have the parents of your Thomas Graham, but it will take some digging. Do you have other Van Buren Co.,MI families?