Based on the previous communications with you , I guess that you are using the PropertySets feature. May, I ask you whether am I right? Basically, RadPropertyGrid relies exclusively on bindings and they will automatically retrieve a property's value, which is the default one if it is not initialized with a new value, so such a customization won't be easy to implement. May, I ask you for some more extensive information on your scenario, so that we could think in its context.
All the best,
the Telerik team