DVT SystemVerilog IDE User Guide
Rev. 19.1.28, 14 August 2019
You can override a function by pressing F4 to open the Type Hierarchy View > enable Show All Inherited Members option (highlighted in the image below) > select a function > right-click > Override
The function's body will be placed at the end of the class.
To override a function from a OVM/UVM/VMM class you have to disable either the Predefined Content Filters for these libraries or the entire Content Filters functionality in order to see the function in the Type Hierarchy View.