Clip and Aggregate
The split and aggregate tools allows you to perform a cut and add on to the polygon at the same time.
Shortcut: CTRL + A
To use the Clip and Aggregate tool, follow the steps outlined below:
Click the Open Transformations button on the Mapping tab.
Select the polygon to clip and aggregate
Select the Clip and Aggregate tool
Draw a line across the polygon where you want the cut to be and where the new polygon added.
Double left click to finish drawing.
Click Save