Regarding #4 - Thomas Eubank Sr. I'm thinking you most likely got the names of the 7 King William Co Va Eubank siblings from information I've posted in the past. If not, let me know and we can share source information. William Trice Eubank was my 4G Grandfather.
Since my last comment, I found a transacript of the marriage between Thomas Eubank Jr and his 2nd wife, Lucy Allen, which lists Thomas Jr's parents as Thomas Sr and Elizabeth Eubank. Additionally, Thomas Sr and his family were in King & Queen County until he purchased property in King William Co near Beulah Baptist Church in 1819. The family remained in King William and many of their descendents still live there.
I have found a considerable amount of information. Are you related to this line?
Kim Wrenn