Dynamically adding children in VLF-ONE

Instance lists may be dynamically expanded by using a relationship handler.

A relationship handler is a special type of snap-in associated with a business object.

The snap-in handler's is defined on the Relationships tab. 

You can see a relationship handler working by using Example Applications -> Advanced -> Dynamic Children.

The filter is DF_T5701O.

The relationship handler is DF_T5702O.

Refer to their source code for a detailed explanation and examples.