To find out why the family went to Indiana, I would search the nearby names found in NC and the same in Indiana. To make a second move (and especially one east) family and church are the normal drawing factors.
We may never know who was with the Forbes, Sawyers & some Whites who came to IL from NC. When my Mother contacted an elderly Curran (Forbes descendant) in the 50s the week before she had thrown out countless letters from the 1800s from family in NC. She never married, was in failing health and felt no one would be interested. We were able to obtain the Forbes family bible. Sadly about a month after we visited her she passed.
Please let me know if you find any NC/IN connections.