In The Witch of Blackbird Pond, what does the overseer of Kit's grandfather's plantation do?

Kit's grandfather owned a plantation in Barbados. He hired a man named Bryant to be the overseer of the plantation. The job of an overseer was to manage the estate and the slaves who worked on it.
Over time, Kit's grandfather's health began to decline. As his health faded, he gave Bryant more responsibilities on the plantation. He did not monitor him as closely. Kit described what had happened the previous winter:

Last winter Bryant sold off the whole crop and then disappeared. Probably he sailed back to England on the trading ship (The Witch of Blackbird Pond, Chapter 3).

Kit and her grandfather were shocked at Bryant's actions. Her grandfather had trusted him. They had depended on the money from the crops to run the plantation and to live on. After Bryant left, her grandfather's health continued to decline. He sank into debt, as he did not have the money from the crops to pay his bills. After her grandfather passed away, Kit sold everything they owned to repay his debts.