diff --git a/projects/ucap-webmessenger-app/src/app/layouts/messenger/dialogs/chat/create-chat.dialog.component.ts b/projects/ucap-webmessenger-app/src/app/layouts/messenger/dialogs/chat/create-chat.dialog.component.ts
index 93da2500..f6a36312 100644
--- a/projects/ucap-webmessenger-app/src/app/layouts/messenger/dialogs/chat/create-chat.dialog.component.ts
+++ b/projects/ucap-webmessenger-app/src/app/layouts/messenger/dialogs/chat/create-chat.dialog.component.ts
@@ -197,15 +197,39 @@ export class CreateChatDialogComponent implements OnInit, OnDestroy {
     );
   }
 
-  onCheckGroup(params: { isChecked: boolean; group: GroupDetailData }) {
-    this.logger.debug(params);
+  onCheckGroup(params: {
+    isChecked: boolean;
+    groupBuddyList: { group: GroupDetailData; buddyList: UserInfo[] };
+  }) {
+    if (params.isChecked) {
+      params.groupBuddyList.buddyList.forEach(item => {
+        if (
+          this.selectedUserList.filter(user => user.seq === item.seq).length ===
+          0
+        ) {
+          this.selectedUserList.push(item);
+        }
+      });
+    } else {
+      this.selectedUserList = this.selectedUserList.filter(
+        item =>
+          params.groupBuddyList.buddyList.filter(del => del.seq === item.seq)
+            .length === 0
+      );
+    }
   }
+
   onCheckUser(params: {
     isChecked: boolean;
     userInfo: UserInfo | UserInfoSS | UserInfoF | UserInfoDN;
   }) {
     if (params.isChecked) {
-      this.selectedUserList.push(params.userInfo);
+      if (
+        this.selectedUserList.filter(user => user.seq === params.userInfo.seq)
+          .length === 0
+      ) {
+        this.selectedUserList.push(params.userInfo);
+      }
     } else {
       this.selectedUserList = this.selectedUserList.filter(
         item => item.seq !== params.userInfo.seq
diff --git a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
index 061fd0ef..8ec6f550 100644
--- a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
+++ b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.html
@@ -28,7 +28,7 @@
           (click)="onClickMore($event, groupBuddy.group)">
           <mat-icon>more_vert</mat-icon>
         </button>
-        <mat-checkbox *ngIf="checkable" #checkbox (change)="onChangeCheck(checkbox.checked, groupBuddy.group)"
+        <mat-checkbox *ngIf="checkable" #checkbox (change)="onChangeCheck(checkbox.checked, groupBuddy)"
           (click)="$event.stopPropagation()"></mat-checkbox>
       </mat-panel-description>
     </mat-expansion-panel-header>
diff --git a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
index 8c021912..a4143cf4 100644
--- a/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
+++ b/projects/ucap-webmessenger-ui-group/src/lib/components/expansion-panel.component.ts
@@ -40,7 +40,7 @@ export class ExpansionPanelComponent implements OnInit {
   @Output()
   checkGroup = new EventEmitter<{
     isChecked: boolean;
-    group: GroupDetailData;
+    groupBuddyList: { group: GroupDetailData; buddyList: UserInfo[] };
   }>();
 
   @ContentChild(ExpansionPanelItemDirective, {
@@ -67,10 +67,13 @@ export class ExpansionPanelComponent implements OnInit {
     this.more.emit({ event, group });
   }
 
-  onChangeCheck(value: boolean, group: GroupDetailData) {
+  onChangeCheck(
+    value: boolean,
+    groupBuddyList: { group: GroupDetailData; buddyList: UserInfo[] }
+  ) {
     this.checkGroup.emit({
       isChecked: value,
-      group
+      groupBuddyList
     });
   }
 }