diff --git a/src/main/java/seedu/address/logic/commands/AddFavouriteCommand.java b/src/main/java/seedu/address/logic/commands/AddFavouriteCommand.java
index 0523b1cd6a9..676528f9cbf 100644
--- a/src/main/java/seedu/address/logic/commands/AddFavouriteCommand.java
+++ b/src/main/java/seedu/address/logic/commands/AddFavouriteCommand.java
@@ -22,6 +22,9 @@ public class AddFavouriteCommand extends Command {
 
     public static final String MESSAGE_SUCCESS = "The following contacts have been added to favourites: %s";
 
+    public static final String MESSAGE_SUCCESS_WITH_WARNING = "The following contacts have been added to favourites: %s"
+            + "\nWarning: There are contacts in your input that were already favourites.";
+
     public static final String MESSAGE_USAGE = COMMAND_WORD
             + ": Adds contacts identified by index number "
             + "as favourites.\n"
@@ -44,22 +47,27 @@ public AddFavouriteCommand(Set<Index> indices) {
     public CommandResult execute(Model model) throws CommandException {
         List<Person> people = model.getFilteredPersonList();
         List<String> modifiedContacts = new ArrayList<>();
+
         boolean anyGreaterThanSize = this.indices.stream().anyMatch(index -> index.getZeroBased() >= people.size());
         if (anyGreaterThanSize) {
             throw new CommandException(Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
         }
+
         boolean anyFavourite = this.indices.stream().anyMatch(index ->
                 people.get(index.getZeroBased()).getIsFavourite());
-        if (anyFavourite) {
-            throw new CommandException(String.format(Messages.MESSAGE_INVALID_COMMAND_FORMAT, MESSAGE_USAGE));
-        }
+
         for (Index index : this.indices) {
             Person person = people.get(index.getZeroBased());
             modifiedContacts.add(person.getName().fullName);
             person.addFavourite();
             model.setPerson(person, person);
         }
+
         model.updateFilteredPersonList(PREDICATE_SHOW_ALL_PERSONS);
+
+        if (anyFavourite) {
+            return new CommandResult(String.format(MESSAGE_SUCCESS_WITH_WARNING, modifiedContacts));
+        }
         return new CommandResult(String.format(MESSAGE_SUCCESS, modifiedContacts));
     }
 
diff --git a/src/main/java/seedu/address/logic/commands/RemoveFavouriteCommand.java b/src/main/java/seedu/address/logic/commands/RemoveFavouriteCommand.java
index 047f4b64e40..9b81a1af4a6 100644
--- a/src/main/java/seedu/address/logic/commands/RemoveFavouriteCommand.java
+++ b/src/main/java/seedu/address/logic/commands/RemoveFavouriteCommand.java
@@ -22,6 +22,9 @@ public class RemoveFavouriteCommand extends Command {
 
     public static final String MESSAGE_SUCCESS = "The following contacts have been removed from favourites: %s";
 
+    public static final String MESSAGE_SUCCESS_WITH_WARNING = "The following contacts have been removed from"
+            + " favourites: %s" + "\nWarning: There are contacts in your input that were already not favourites.";
+
     public static final String MESSAGE_USAGE = COMMAND_WORD
             + ": Removes contacts identified by index number "
             + "as favourites.\n"
@@ -52,9 +55,6 @@ public CommandResult execute(Model model) throws CommandException {
 
         boolean anyNotFavourite = this.indices.stream().anyMatch(index ->
                 !people.get(index.getZeroBased()).getIsFavourite());
-        if (anyNotFavourite) {
-            throw new CommandException(String.format(Messages.MESSAGE_INVALID_COMMAND_FORMAT, MESSAGE_USAGE));
-        }
 
         for (Index index : this.indices) {
             Person person = people.get(index.getZeroBased());
@@ -62,7 +62,12 @@ public CommandResult execute(Model model) throws CommandException {
             person.removeFavourite();
             model.setPerson(person, person);
         }
+
         model.updateFilteredPersonList(PREDICATE_SHOW_ALL_PERSONS);
+
+        if (anyNotFavourite) {
+            return new CommandResult(String.format(MESSAGE_SUCCESS_WITH_WARNING, modifiedContacts));
+        }
         return new CommandResult(String.format(MESSAGE_SUCCESS, modifiedContacts));
     }
 
diff --git a/src/test/java/seedu/address/logic/commands/AddFavouriteCommandTest.java b/src/test/java/seedu/address/logic/commands/AddFavouriteCommandTest.java
index 04a2f579b5d..8676dd5a9cb 100644
--- a/src/test/java/seedu/address/logic/commands/AddFavouriteCommandTest.java
+++ b/src/test/java/seedu/address/logic/commands/AddFavouriteCommandTest.java
@@ -38,7 +38,7 @@ public void constructor_nullIndices_throwsNullPointerException() {
     @Test
     public void execute_addFavourite_success() {
         Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
-        Person editedPerson = new PersonBuilder(firstPerson).withFavourite(true).build();
+        Person editedPerson = new PersonBuilder(firstPerson).build();
         Set<Index> indices = Set.of(Index.fromOneBased(1));
         List<String> modifiedContacts = List.of(firstPerson.getName().fullName);
         AddFavouriteCommand addFavouriteCommand = new AddFavouriteCommand(indices);
@@ -59,14 +59,20 @@ public void execute_invalidIndex_throwsCommandException() {
     }
 
     @Test
-    public void execute_favouriteContact_throwsCommandException() {
+    public void execute_alreadyFavourite_success() {
         Set<Index> indices = Set.of(Index.fromOneBased(1));
         Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
         Person editedPerson = new PersonBuilder(firstPerson).withFavourite(true).build();
         model.setPerson(firstPerson, editedPerson);
         AddFavouriteCommand addFavouriteCommand = new AddFavouriteCommand(indices);
-        assertThrows(CommandException.class, MESSAGE_INVALID_FORMAT, () ->
-                addFavouriteCommand.execute(model));
+
+        List<String> modifiedContacts = List.of(firstPerson.getName().fullName);
+        String expectedMessage = String.format(AddFavouriteCommand.MESSAGE_SUCCESS_WITH_WARNING, modifiedContacts);
+
+        Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
+        expectedModel.setPerson(model.getFilteredPersonList().get(0), editedPerson);
+
+        assertCommandSuccess(addFavouriteCommand, model, expectedMessage, expectedModel);
     }
 
     @Test
diff --git a/src/test/java/seedu/address/logic/commands/RemoveFavouriteCommandTest.java b/src/test/java/seedu/address/logic/commands/RemoveFavouriteCommandTest.java
index 4b42f2ae1b3..c4cf665ed9e 100644
--- a/src/test/java/seedu/address/logic/commands/RemoveFavouriteCommandTest.java
+++ b/src/test/java/seedu/address/logic/commands/RemoveFavouriteCommandTest.java
@@ -44,7 +44,6 @@ public void execute_removeFavourite_success() {
         List<String> modifiedContacts = List.of(firstPerson.getName().fullName);
         RemoveFavouriteCommand removeFavouriteCommand = new RemoveFavouriteCommand(indices);
         String expectedMessage = String.format(RemoveFavouriteCommand.MESSAGE_SUCCESS, modifiedContacts);
-
         Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
 
         assertCommandSuccess(removeFavouriteCommand, model, expectedMessage, expectedModel);
@@ -59,11 +58,17 @@ public void execute_invalidIndex_throwsCommandException() {
     }
 
     @Test
-    public void execute_nonFavouriteContact_throwsCommandException() {
-        Set<Index> indices = Set.of(Index.fromOneBased(2));
+    public void execute_alreadyNonFavouriteContact_success() {
+        Person firstPerson = model.getFilteredPersonList().get(INDEX_FIRST_PERSON.getZeroBased());
+        Person editedPerson = new PersonBuilder(firstPerson).withFavourite(false).build();
+        model.setPerson(firstPerson, editedPerson);
+        Set<Index> indices = Set.of(Index.fromOneBased(1));
+        List<String> modifiedContacts = List.of(firstPerson.getName().fullName);
         RemoveFavouriteCommand removeFavouriteCommand = new RemoveFavouriteCommand(indices);
-        assertThrows(CommandException.class, MESSAGE_INVALID_FORMAT, () ->
-                removeFavouriteCommand.execute(model));
+        String expectedMessage = String.format(RemoveFavouriteCommand.MESSAGE_SUCCESS_WITH_WARNING, modifiedContacts);
+        Model expectedModel = new ModelManager(new AddressBook(model.getAddressBook()), new UserPrefs());
+
+        assertCommandSuccess(removeFavouriteCommand, model, expectedMessage, expectedModel);
     }
 
     @Test