You can update a user defined property when split/merge tools are used against a polygon. For example, perhaps you have a property called DateChanged and you'd like that field to automatically update when the polygon is split or merged.
To do that, make use of Initial Values in the DateChanged property.
The following initial value keys are available which are used to determine the current action to which the value should be applied:
These initial values are added to the property to be automatically changed. In this example, that's the DateChanged property.
A sample schema is provided for your learning.