Angular Ivy - Adding dynamic controls to an existing form groups within form array

Question

Using Angular Reactive Forms module, i have a case where my form array being populated with few form groups, in a specific case for example "on destroy" i would like to add controls to each of the form groups inside my form array, i tried iterating over the array and using addcontrol but something mess up smh, code below thanks for help

<FormArray>this.form.get('additionals')).controls.forEach(
    (control) => {console.log(
      control.addControl('new', new FormControl('', Validators.required))
    )}

in result i get > Property 'addControl' does not exist on type 'AbstractControl'. i dont know why i get such error, as far as i know from Angular io docs addControl is method of AbstractControl which FormGroup is instance of it. so why it error?