I too am a Blackwell, although I don't think from the same line.
I thought you should know that
"laws passed in North Carolina in the 1740's gave the word mulatto very precise legal definitions. I understand that mulatto legally referred to either the child of an ''Indian/white'' union , or to a person descended from an African-American within three generations"

"it should be remebered however, that anyone not thought of as White was labeled Free Colored."

Also, a white man with a dark tan could have been labled as mulatto as well.