Birden çok istek nasıl beklenir

Birden fazla isteği beklemenin ve bittiğinde bir şeyler yapmanın en iyi yolunun ne olduğunu anlamaya çalışıyorum, her ikisinin de aynı anda öğle yemeği talep ettiğini ve birbirlerini beklememeleri gerektiğini unutmayın.

  // table filling
  public SUB_getActSearch: Subscription;


  // table filling 2
  public SUB_getDeclarationSearch: Subscription;

  public fillTable(): void {
    const searchOBJ = {
      CreateDateFrom: this.currentDate,
      CreateDateTo: this.currentDate,
      ActNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      vinCode: this.vinCode == undefined ? '' : this.vinCode,
      GovNumber: this.GovNumber == undefined ? '' : this.GovNumber,
      IsFromDashboard: true
    };
    const searchOBJ2 = {
      ActNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      vinCode: this.vinCode == undefined ? '' : this.vinCode,
      GovNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    if ((this.ActNumber && this.ActNumber != undefined && this.ActNumber != null) || (this.vinCode && this.vinCode != undefined && this.vinCode != null) || (this.GovNumber && this.GovNumber != undefined && this.GovNumber != null)) {
      this.SUB_getActSearch = this.searchService.getActSearch({ ...searchOBJ2, PageSize: this.pageSize, PageNumber: this.currentPage }).subscribe((res) => {
        this.Act_Data = [];
        let headerPagin = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLength = headerPagin.totalCount;
        this.currentPage = headerPagin.currentPage;
        this.pageSize = headerPagin.pageSize;
        res.body.map((param) => {
          this.Act_Data.push(param);
        });
        this.ActDataSource = new MatTableDataSource<Element>(this.Act_Data);
        // console.log('Your form data : ', this.ActDataSource);
      });
    } else {
      this.SUB_getActSearch = this.searchService.getActSearch({ ...searchOBJ, PageSize: this.pageSize, PageNumber: this.currentPage }).subscribe((res) => {
        this.Act_Data = [];
        let headerPagin = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLength = headerPagin.totalCount;
        this.currentPage = headerPagin.currentPage;
        this.pageSize = headerPagin.pageSize;
        res.body.map((param) => {
          this.Act_Data.push(param);
        });
        this.ActDataSource = new MatTableDataSource<Element>(this.Act_Data);
        // console.log('Your form data : ', this.ActDataSource);
      });
    }
  }


  public fillTable2(): void {
    const searchOBJ = {
      DeclarationCreateDateFrom: this.currentDate.substring(0, 10),
      DeclarationCreateDateTo: this.currentDate,
      DeclarationNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      VinCode: this.vinCode == undefined ? '' : this.vinCode,
      TransitNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    const searchOBJ2 = {
      DeclarationNumber: this.ActNumber == undefined ? '' : this.ActNumber,
      VinCode: this.vinCode == undefined ? '' : this.vinCode,
      TransitNumber: this.GovNumber == undefined ? '' : this.GovNumber,
    };
    if ((this.ActNumber && this.ActNumber != undefined && this.ActNumber != null) || (this.vinCode && this.vinCode != undefined && this.vinCode != null) || (this.GovNumber && this.GovNumber != undefined && this.GovNumber != null)) {
      this.SUB_getDeclarationSearch = this.declarationsService.getDeclarations({ ...searchOBJ, IsFromDashboard: true, PageSize: this.pageSizeDecl, PageNumber: this.currentPageDecl }).subscribe((res) => {
        this.Declaration_Data = [];
        let headerPaginDecl = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLengthDecl = headerPaginDecl.totalCount;
        this.currentPageDecl = headerPaginDecl.currentPage;
        this.pageSizeDecl = headerPaginDecl.pageSize;
        res.body.map((param) => {
          this.Declaration_Data.push(param);
        });
        this.DeclarationDataSource = new MatTableDataSource<Element>(this.Declaration_Data);
        // console.log('Your form data : ', this.DeclarationDataSource);
      });
    } else {
      this.SUB_getDeclarationSearch = this.declarationsService.getDeclarations({ ...searchOBJ, IsFromDashboard: true, PageSize: this.pageSizeDecl, PageNumber: this.currentPageDecl }).subscribe((res) => {
        this.Declaration_Data = [];
        let headerPaginDecl = JSON.parse(res.headers.get('X-Pagination'));
        this.elementsLengthDecl = headerPaginDecl.totalCount;
        this.currentPageDecl = headerPaginDecl.currentPage;
        this.pageSizeDecl = headerPaginDecl.pageSize;
        res.body.map((param) => {
          this.Declaration_Data.push(param);
        });
        this.DeclarationDataSource = new MatTableDataSource<Element>(this.Declaration_Data);
        // console.log('Your form data : ', this.DeclarationDataSource);
      });
    }
  }

Ngoninit içinde çağrılan iki yöntem vardır: fillTable() ve fillTable2().

Abonelikleri dinlemek ve beklemek için aşağıdaki yöntemi kullanmaya çalıştım

  public testingforkJoin(): void {
    forkJoin([this.SUB_getActSearch, this.SUB_getDeclarationSearch]
    ).subscribe(val => 
console.log("xxxxx", val));
// call some method here as soon as both are done
  }

Ancak forkjoin'in abonelikleri dinleyemediği ortaya çıktıkça, abonelikler için forkjoin'e benzer başka bir yol var mı?

HTTP isteklerini içeren çekme yöntemleri var ve her iki ağ isteğinin tamamlanmasını beklemek ve tamamlandıktan hemen sonra bir şeyler yapmak istiyorum.