diff --git a/src/app/core/data/data.service.ts b/src/app/core/data/data.service.ts
index e91143a8cf..fc4da69a5c 100644
--- a/src/app/core/data/data.service.ts
+++ b/src/app/core/data/data.service.ts
@@ -161,7 +161,6 @@ export abstract class DataService<T extends CacheableObject> {
   }
 
   findByHref(href: string, options?: HttpOptions): Observable<RemoteData<T>> {
-    console.log('perform request for:', href)
     this.requestService.configure(new GetRequest(this.requestService.generateRequestId(), href, null, options), this.forceBypassCache);
     return this.rdbService.buildSingle<T>(href);
   }
diff --git a/src/app/core/data/relationship.service.ts b/src/app/core/data/relationship.service.ts
index b93f4f6ea4..a8e8874dfe 100644
--- a/src/app/core/data/relationship.service.ts
+++ b/src/app/core/data/relationship.service.ts
@@ -68,7 +68,7 @@ export class RelationshipService extends DataService<Relationship> {
   deleteRelationship(id: string): Observable<RestResponse> {
     return this.getRelationshipEndpoint(id).pipe(
       isNotEmptyOperator(),
-      distinctUntilChanged(),
+      take(1),
       map((endpointURL: string) => new DeleteRequest(this.requestService.generateRequestId(), endpointURL)),
       configureRequest(this.requestService),
       switchMap((restRequest: RestRequest) => this.requestService.getByUUID(restRequest.uuid)),
@@ -84,7 +84,7 @@ export class RelationshipService extends DataService<Relationship> {
     options.headers = headers;
     return this.halService.getEndpoint(this.linkPath).pipe(
       isNotEmptyOperator(),
-      distinctUntilChanged(),
+      take(1),
       map((endpointUrl: string) => `${endpointUrl}?relationshipType=${typeId}`),
       map((endpointURL: string) => new PostRequest(this.requestService.generateRequestId(), endpointURL, `${item1.self} \n ${item2.self}`, options)),
       configureRequest(this.requestService),
@@ -267,7 +267,7 @@ export class RelationshipService extends DataService<Relationship> {
             );
           }))
         }),
-        map((relationships: Relationship[]) => relationships.find((relationship => hasValue(relationship)))),
+        map((relationships: Relationship[]) => relationships.find((relationship => hasValue(relationship))))
       )
   }
 
diff --git a/src/app/core/data/request.service.ts b/src/app/core/data/request.service.ts
index 775118dbc0..381fbd58c5 100644
--- a/src/app/core/data/request.service.ts
+++ b/src/app/core/data/request.service.ts
@@ -308,6 +308,7 @@ export class RequestService {
    */
   hasByHref(href: string): boolean {
     let result = false;
+    /* NB: that this is only a solution because the select method is synchronous, see: https://github.com/ngrx/store/issues/296#issuecomment-269032571*/
     this.getByHref(href).pipe(
       take(1)
     ).subscribe((requestEntry: RequestEntry) => result = this.isValid(requestEntry));
diff --git a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.html b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.html
index 2039a86d0f..a38f557219 100644
--- a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.html
+++ b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.html
@@ -44,15 +44,16 @@
                     <div ngbDropdown class="input-group-append">
                         <button *ngIf="selectAllLoading" type="button"
                                 class="btn btn-outline-secondary rounded-right">
-                        <span class="spinner-border spinner-border-sm" role="status"
+                            <span class="spinner-border spinner-border-sm" role="status"
                               aria-hidden="true"></span>
                             <span class="sr-only">{{ ('submission.sections.describe.relationship-lookup.loading' | translate) }}</span>
                         </button>
-                        <button *ngIf="!selectAllLoading" id="resultdropdown" type="button"
+                        <button id="resultdropdown" type="button"
                                 ngbDropdownToggle
                                 class="btn btn-outline-secondary dropdown-toggle-split"
                                 data-toggle="dropdown" aria-haspopup="true"
-                                aria-expanded="false">
+                                aria-expanded="false"
+                                [hidden]="selectAllLoading">
                             <span class="sr-only">{{ ('submission.sections.describe.relationship-lookup.toggle-dropdown' | translate) }}</span>
                         </button>
                         <div ngbDropdownMenu aria-labelledby="resultdropdown">
diff --git a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
index e22a9a442d..22343f67b3 100644
--- a/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
+++ b/src/app/shared/form/builder/ds-dynamic-form-ui/relation-lookup-modal/dynamic-lookup-relation-modal.component.ts
@@ -2,13 +2,13 @@ import { Component, OnDestroy, OnInit } from '@angular/core';
 import { PaginatedList } from '../../../../../core/data/paginated-list';
 import { SearchResult } from '../../../../search/search-result.model';
 import { RemoteData } from '../../../../../core/data/remote-data';
-import { Observable, ReplaySubject } from 'rxjs';
+import { from, Observable, ReplaySubject } from 'rxjs';
 import { SearchService } from '../../../../../core/shared/search/search.service';
 import { PaginatedSearchOptions } from '../../../../search/paginated-search-options.model';
 import { DSpaceObject } from '../../../../../core/shared/dspace-object.model';
 import { PaginationComponentOptions } from '../../../../pagination/pagination-component-options.model';
 import { NgbActiveModal } from '@ng-bootstrap/ng-bootstrap';
-import { hasValue, isNotEmpty } from '../../../../empty.util';
+import { hasValue, hasValueOperator, isNotEmpty } from '../../../../empty.util';
 import { concat, map, mergeMap, multicast, switchMap, take, takeWhile, tap } from 'rxjs/operators';
 import { Router } from '@angular/router';
 import { SEARCH_CONFIG_SERVICE } from '../../../../../+my-dspace-page/my-dspace-page.component';
@@ -117,12 +117,24 @@ export class DsDynamicLookupRelationModalComponent implements OnInit, OnDestroy
     });
   }
 
-  selectPage(page: SearchResult<DSpaceObject>[]) {
+  selectPage(page: SearchResult<Item>[]) {
+    this.selection$
+      .pipe(take(1))
+      .subscribe((selection: SearchResult<Item>[]) => {
+        const filteredPage = page.filter((pageItem) => selection.findIndex((selected) => selected.equals(pageItem)) < 0)
+        this.select(...filteredPage);
+      });
     this.selectableListService.select(this.listId, page);
   }
 
-  deselectPage(page: SearchResult<DSpaceObject>[]) {
+  deselectPage(page: SearchResult<Item>[]) {
     this.allSelected = false;
+    this.selection$
+      .pipe(take(1))
+      .subscribe((selection: SearchResult<Item>[]) => {
+        const filteredPage = page.filter((pageItem) => selection.findIndex((selected) => selected.equals(pageItem)) >= 0)
+        this.deselect(...filteredPage);
+      });
     this.selectableListService.deselect(this.listId, page);
   }
 
@@ -132,62 +144,84 @@ export class DsDynamicLookupRelationModalComponent implements OnInit, OnDestroy
     const fullPagination = Object.assign(new PaginationComponentOptions(), {
       query: this.searchQuery,
       currentPage: 1,
-      pageSize: Number.POSITIVE_INFINITY
+      pageSize: 9999
     });
     const fullSearchConfig = Object.assign(this.searchConfig, { pagination: fullPagination });
-    const results = this.searchService.search(fullSearchConfig);
-    results.pipe(
+    const results$ = this.searchService.search(fullSearchConfig) as Observable<RemoteData<PaginatedList<SearchResult<Item>>>>;
+    results$.pipe(
       getSucceededRemoteData(),
       map((resultsRD) => resultsRD.payload.page),
       tap(() => this.selectAllLoading = false),
-    ).subscribe((results) =>
-      this.selectableListService.select(this.listId, results)
+    ).subscribe((results) => {
+        this.selection$
+          .pipe(take(1))
+          .subscribe((selection: SearchResult<Item>[]) => {
+            const filteredResults = results.filter((pageItem) => selection.findIndex((selected) => selected.equals(pageItem)) < 0);
+            this.select(...filteredResults);
+          });
+        this.selectableListService.select(this.listId, results);
+      }
     );
   }
 
   deselectAll() {
     this.allSelected = false;
+    this.selection$
+      .pipe(take(1))
+      .subscribe((selection: SearchResult<Item>[]) => this.deselect(...selection));
     this.selectableListService.deselectAll(this.listId);
   }
 
 
-  select(selectableObject: SearchResult<Item>) {
+  select(...selectableObjects: SearchResult<Item>[]) {
     setTimeout(() => this.itemRD$
       .pipe(
         getSucceededRemoteData(),
-        mergeMap((itemRD: RemoteData<Item>) => {
+        switchMap((itemRD: RemoteData<Item>) => {
           const type1: string = itemRD.payload.firstMetadataValue('relationship.type');
-          const type2: string = selectableObject.indexableObject.firstMetadataValue('relationship.type');
-          return this.relationshipTypeService.getRelationshipTypeByLabelAndTypes(this.relationship.relationshipType, type1, type2)
-            .pipe(
-              mergeMap((type: RelationshipType) => {
-                  const isSwitched = type.rightLabel === this.relationship.relationshipType;
-                  if (isSwitched) {
-                    return this.relationshipService.addRelationship(type.id, selectableObject.indexableObject, itemRD.payload);
-                  } else {
-                    return this.relationshipService.addRelationship(type.id, itemRD.payload, selectableObject.indexableObject);
-                  }
-                }
-              )
-            );
+          return from(selectableObjects).pipe(
+            mergeMap((object) => {
+              const type2: string = object.indexableObject.firstMetadataValue('relationship.type');
+              return this.relationshipTypeService.getRelationshipTypeByLabelAndTypes(this.relationship.relationshipType, type1, type2)
+                .pipe(
+                  mergeMap((type: RelationshipType) => {
+                      const isSwitched = type.rightLabel === this.relationship.relationshipType;
+                      if (isSwitched) {
+                        return this.relationshipService.addRelationship(type.id, object.indexableObject, itemRD.payload);
+                      } else {
+                        return this.relationshipService.addRelationship(type.id, itemRD.payload, object.indexableObject);
+                      }
+                    }
+                  )
+                ).pipe(take(1));
+            }));
         }),
-        take(1)
-      )
-      .subscribe(), 0);
+      ).subscribe(), 0
+    );
   }
 
 
-  deselect(selectableObject: SearchResult<Item>) {
+  deselect(...selectableObjects: SearchResult<Item>[]) {
     setTimeout(() => this.itemRD$.pipe(
       getSucceededRemoteData(),
-      switchMap((itemRD: RemoteData<Item>) => this.relationshipService.getRelationshipByItemsAndLabel(itemRD.payload, selectableObject.indexableObject, this.relationship.relationshipType)),
-      switchMap((relationship: Relationship) => this.relationshipService.deleteRelationship(relationship.id)),
+      switchMap((itemRD: RemoteData<Item>) => {
+        return from(selectableObjects).pipe(
+          tap(t => console.log(itemRD)),
+          mergeMap((object) => this.relationshipService.getRelationshipByItemsAndLabel(itemRD.payload, object.indexableObject, this.relationship.relationshipType)),
+          take(1),
+          hasValueOperator(),
+          mergeMap((relationship: Relationship) => this.relationshipService.deleteRelationship(relationship.id))
+        )
+      }),
       take(1),
     ).subscribe(), 0);
   }
 
-  ngOnDestroy(): void {
-    if (hasValue(this.subscription)) {
+  ngOnDestroy()
+    :
+    void {
+    if (hasValue(this.subscription)
+    ) {
       this.subscription.unsubscribe();
     }
   }