Control record navigation on MDI child form from MDI parent form

Question

I have Form A (MDI parent) that has a BindingNavigator control. Using this BindingNavigator I would like it to navigate the records of a DataGridView on Form B (MDI Child).

So far on the load event of Form B I have tried to set the binding source of Form A BindingNavigator control but this has not worked. Code below. Any help appreciated.

FormA frm = new FormA();
frm. BindingNavigator.BindingSource = this.FormBDataGridViewBindingSource;