What is Subdivide?

Legal Definition
To divide a part of a thing which has already been divided. For example, when a person dies leaving children, and grandchildren, the children of one of his own who is dead, his property is divided into as many shares as he had children, including the deceased, and the share of the deceased is subdivided into as many shares as he had children.
-- Bouviers Law Dictionary
Legal Definition
To divide a part into smaller parts; to separate into smaller divisions. As, where an estate is to be token by some of the heirs per stirpes, it is divided and subdivided according to the number of inkers in the nearest degree and those in the more remote degree respectively.
-- Black's Law Dictionary