Angular4 - execute function if NOT all checkboxes are selected

I have a main checkbox which has ngModel value as [(ngModel)]="formModel.acknowledged1" and on component it is set to false like formModel = { acknowledged1 :false }

and i have a table with n number of rows, each row having checkboxes associated with ngModel as [(ngModel)]="formModel.acknowledged1" so when i click on main checkbox, all checkboxes on tables get selected and then my function deleterow gets executed, but i want if i select only singly checkbox from table rows, then some other function should get executed. see below to make my question clear. html -

     <p>
     <checkbox  [(ngModel)]="formModel.acknowledged1"  id="box1"   name="acknowledgement1"></checkbox></p>

     <tbody  infiniteScroll
                    [infiniteScrollDistance]="2"
                    [infiniteScrollThrottle]="300"
                    (scrolled)="onScroll()"
                    [scrollWindow]="false">


    <ng-container *ngFor="let data of allData>
                        <tr class= "row-break">

                         <checkbox    [(ngModel)]="formModel.acknowledged1" id="box2"  name="acknowledgement2">
                     </checkbox>

                            <td>
                                 <a></a>
                            </td>
                            <td>
                                
                            </td>
                        </tr>
                    </ng-container>
                </tbody>
component.ts -


 export class CodesComponent implements OnInit{                                
  formModel = {
   acknowledged1 :false
   }                              
   ngOnInit (){

deleterow(){
        if(this.formModel.acknowledged1==true){
        this.reasonCodesActions.deleterow();
      } 



deletesinglerow(){

}
 }