From what I see on SubSonic 2 source code, when you trigger the btnSave_Click there is no other function that you can call as it is.
So you need to modified the source code and recreate the subsonic 2 dll (that is very easy).
So if you modify the source code, just place a function that runs after the save, then on your code override this function with your call.
/// <summary>
/// Saves the editor.
/// </summary>
private void SaveEditor()
{
if(Mode == ScaffoldMode.Edit)
UpdateRecord(PrimaryKeyControlValue);
else
InsertRecord();
SaveManyToMany();
AfterTheSave();
if(ReturnOnSave)
BuildWithModeChange(ScaffoldMode.List);
}
public virtual void AfterTheSave()
{
}