Instead of slicing a piece in two, if there is more than one line inside a piece, you can use these lines to divide the piece into multiple pieces.
To divide a piece into multiple pieces:
If the piece does not already have the internal lines needed for the divide operation, add them to the piece. You must ensure that each such line:
Runs from edge to edge
Is set as a Cut Mark
To set a line as a Cut Mark:
In the 2D window, click the line.
Go to the Context view, in the Line Properties section.
Select Cut Mark.
On the Main toolbar, click Select.
On the Horizontal contextual menu, ensure Pieces is selected.
In the 2D window, click the piece you want to divide.
Go to the Context view, in the Actions section.
The piece is divided along the lines.
The following image shows a piece being divided.