I am using a mmMaintenanceForm as a base form. Following the new documentation I created a FilterDefaultValues class and HookSetDefaultValues method in the Filters business object. If I create a brand new myButton and put oFilters.NewRow(new FilterDefaultValues(("MyDef1","MyDef2")) into the myButton_Click method, I get what I expect: a new row with my default values. However, I need to use New button that belongs to the base form.
I tried this:

protected override void btnNew_Click(object sender, System.EventArgs e)
 {
    oFilters.NewRow(new FiltersDefaultValues("MyDef1","MyDef2"));
 }

I got three (?) new rows, two of them with my default values and one without them.
How can I keep all functionalities of mmButtonNew, but not create extra new rows?

Thanks in advance

Slava