I do not think my brother will ever marry again, and certainly not her; and this is why: first, I know that though he rarely speaks about the wife he has lost, the grief of that loss has gone too deep in his heart for him ever to decide to give her a successor and our little angel a stepmother.
There are no more uses of "successor" in the book.
Show samples from other sources
He was President Lincoln’s successor.
The manager is nearing retirement, so they are searching for a successor.