OK Greg,
I surrender on subclassing :)
Back to your original question at what point you need to know the change dynamicbackcolor/controlsource ?

At the least it would invoke grid access (this_access). However that sounds to be an overload for grid.

How might a dynamicbackcolor change ?
1) In code
2) ?

How might a controlsource change ?
1) In code
2) Grid.recordsource
3) ?

In code portions are under your direct control. Grid.recordsource would need one _assign method.

Honestly I started to suspect I understood your original question.
Cetin