app-parent.js

// app-parent.ts
@Component({
  selector: 'example-parent',
  template: `./example-parent.html`,
  styleUrls: ['./parent.component.css']
})
export class ParentComponent implements OnInit {

  formBroadcast: Subject<FormGroup> = new BehaviorSubject(null);

  form: FormGroup;

  constructor(
      private formBuilder: FormBuilder
  ) { }

  ngOnInit() {
      this.createForm();
      this.subscribeForm();
  }

  subscribeForm(): void {
    this.formBroadcast.subscribe(e => {
      const { name, age } = e;
      this.form.get('name').setValue(name);
      this.form.get('age').setValue(age);
    })
  }

  createForm(): void {
      this.form = this.formBuilder.group({
          name: new FormControl(''),
          age: new FormControl(-1)
      });
  }
}