diff --git a/OwnChar/Data/IDataManager.cs b/OwnChar/Data/IDataManager.cs
index 1013d01..3e6cbe2 100644
--- a/OwnChar/Data/IDataManager.cs
+++ b/OwnChar/Data/IDataManager.cs
@@ -14,10 +14,17 @@ public interface IDataManager
     abstract bool DeleteUserAccount(UserAccount account);
 
     // Group management
-    abstract UserProfile? GetOwner(Group group);
-    abstract IEnumerable<UserProfile>? GetMembers(Group group);
+    abstract UserProfile? GetOwner(UserAccount account, Group group);
+    abstract IEnumerable<UserProfile>? GetMembers(UserAccount account, Group group);
+    abstract bool AddMember(UserAccount account, Group group, UserProfile user);
+    abstract bool RemoveMember(UserAccount account, Group group, UserProfile user);
+    abstract Group? CreateGroup(UserAccount account, string name);
+    abstract bool DeleteGroup(UserAccount account, Group group);
 
     // Character management
-    abstract IEnumerable<Character>? GetCharacters(Group group);
-    abstract IEnumerable<Character>? GetCharacters(UserProfile profile);
+    abstract UserProfile? GetOwner(UserAccount account, Character group);
+    abstract IEnumerable<Character>? GetCharacters(UserAccount account, Group group);
+    abstract IEnumerable<Character>? GetCharacters(UserAccount account, UserProfile profile);
+    abstract Character? CreateCharacter(UserAccount account, string name, Group? group);
+    abstract bool DeleteCharacter(UserAccount account, Character character);
 }
diff --git a/OwnChar/Data/IDataProvider.cs b/OwnChar/Data/IDataProvider.cs
index 01716fa..d7bdfcd 100644
--- a/OwnChar/Data/IDataProvider.cs
+++ b/OwnChar/Data/IDataProvider.cs
@@ -23,9 +23,13 @@ public interface IDataProvider
     // Gets
     abstract UserAccount? GetUserAccount(string username, string password);
     abstract UserProfile? GetUserProfile(string username);
-    abstract IEnumerable<UserProfile>? GetGroupMembers(Group group);
+    abstract IEnumerable<UserProfile>? GetMembers(Group group);
     abstract UserProfile? GetOwner(Group group);
     abstract UserProfile? GetOwner(Character character);
     abstract IEnumerable<Character>? GetCharacters(Group group);
     abstract IEnumerable<Character>? GetCharacters(UserProfile jprofile);
+
+    // Sets
+    abstract bool AddMember(Group group, UserProfile user);
+    abstract bool RemoveMember(Group group, UserProfile user);
 }
diff --git a/OwnChar/Data/Managers/DefaultDataManager.cs b/OwnChar/Data/Managers/DefaultDataManager.cs
index d172b60..51c390d 100644
--- a/OwnChar/Data/Managers/DefaultDataManager.cs
+++ b/OwnChar/Data/Managers/DefaultDataManager.cs
@@ -15,16 +15,27 @@ public class DefaultDataManager : IDataManager
         Initialize(false);
     }
 
-    public IEnumerable<UserProfile>? GetMembers(Group group)
+    public IEnumerable<UserProfile>? GetMembers(UserAccount account, Group group)
     {
-        return DataProvider.GetGroupMembers(group);
+        if (!account.HasPermission(UserType.Guest))
+            return null;
+        return DataProvider.GetMembers(group);
     }
 
-    public UserProfile? GetOwner(Group group)
+    public UserProfile? GetOwner(UserAccount account, Group group)
     {
+        if (!account.HasPermission(UserType.Guest))
+            return null;
         return DataProvider.GetOwner(group);
     }
 
+    public UserProfile? GetOwner(UserAccount account, Character character)
+    {
+        if (!account.HasPermission(UserType.Guest))
+            return null;
+        return DataProvider.GetOwner(character);
+    }
+
     public UserProfile? GetUserProfile(UserAccount account)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(account.Username, nameof(account.Username));
@@ -88,13 +99,79 @@ public class DefaultDataManager : IDataManager
         return true;
     }
 
-    public IEnumerable<Character>? GetCharacters(Group group)
+    public IEnumerable<Character>? GetCharacters(UserAccount account, Group group)
     {
+        if (!account.HasPermission(UserType.Guest))
+            return null;
         return DataProvider.GetCharacters(group);
     }
 
-    public IEnumerable<Character>? GetCharacters(UserProfile profile)
+    public IEnumerable<Character>? GetCharacters(UserAccount account, UserProfile profile)
     {
+        if (!account.HasPermission(UserType.Guest))
+            return null;
         return DataProvider.GetCharacters(profile);
     }
+
+    public bool AddMember(UserAccount account, Group group, UserProfile user)
+    {
+        if (GetUserProfile(account) is not UserProfile profile || DataProvider.GetOwner(group) is not UserProfile owner || !account.HasPermission(profile == owner ? UserType.User : UserType.Admin))
+            return false;
+        return DataProvider.AddMember(group, user);
+    }
+
+    public bool RemoveMember(UserAccount account, Group group, UserProfile user)
+    {
+        if (GetUserProfile(account) is not UserProfile profile || DataProvider.GetOwner(group) is not UserProfile owner || !account.HasPermission(profile == owner ? UserType.User : UserType.Admin))
+            return false;
+        return DataProvider.RemoveMember(group, user);
+    }
+
+    public Group? CreateGroup(UserAccount account, string name)
+    {
+        if (!account.HasPermission(UserType.User) || GetUserProfile(account) is not UserProfile profile || DataProvider.Create<Group>() is not Group group)
+            return null;
+
+        group.Name = name;
+
+        DataProvider.Save(group);
+
+        DataProvider.SetOwner(group, profile);
+
+        return group;
+    }
+
+    public bool DeleteGroup(UserAccount account, Group group)
+    {
+        if (GetUserProfile(account) is not UserProfile profile || DataProvider.GetOwner(group) is not UserProfile owner || !account.HasPermission(profile == owner ? UserType.User : UserType.Admin))
+            return false;
+        return DataProvider.Delete(group);
+    }
+
+    public Character? CreateCharacter(UserAccount account, string name, Group? group)
+    {
+        if (!account.HasPermission(UserType.User) || GetUserProfile(account) is not UserProfile profile || DataProvider.Create<Character>() is not Character character)
+            return null;
+
+        character.Name = name;
+
+        DataProvider.Save(character);
+
+        DataProvider.SetOwner(character, profile);
+
+        if (group != null)
+            DataProvider.SetParent(character, group);
+
+        return character;
+    }
+
+    public bool DeleteCharacter(UserAccount account, Character character)
+    {
+        if (GetUserProfile(account) is not UserProfile profile || DataProvider.GetOwner(character) is not UserProfile owner || !account.HasPermission(profile == owner ? UserType.User : UserType.Admin))
+            return false;
+
+        DataProvider.Delete(character);
+
+        return true;
+    }
 }
diff --git a/OwnChar/Data/Providers/JsonFile/JsonFileDataProvider.cs b/OwnChar/Data/Providers/JsonFile/JsonFileDataProvider.cs
index 7608e8e..047d7d2 100644
--- a/OwnChar/Data/Providers/JsonFile/JsonFileDataProvider.cs
+++ b/OwnChar/Data/Providers/JsonFile/JsonFileDataProvider.cs
@@ -131,7 +131,7 @@ public class JsonFileDataProvider : IDataProvider
         {
             // We don't delete profiles at the moment!
             profile.Name = "Deleted user";
-            return false;
+            return true;
         }
 
         return false;
@@ -201,7 +201,7 @@ public class JsonFileDataProvider : IDataProvider
         return JsonFile.UserAccounts.FirstOrDefault(n => n.Username == username)?.Profile;
     }
 
-    public IEnumerable<UserProfile>? GetGroupMembers(Group group)
+    public IEnumerable<UserProfile>? GetMembers(Group group)
     {
         if (group is JsonGroup jgroup)
             return jgroup.Members;
@@ -235,4 +235,25 @@ public class JsonFileDataProvider : IDataProvider
             return JsonFile.Characters.Where(n => n.Owner == profile);
         return null;
     }
+
+    public bool AddMember(Group group, UserProfile user)
+    {
+        if (group is JsonGroup jgroup && user is JsonUserProfile jprofile)
+        {
+            if (!jgroup.Members.Contains(jprofile))
+                jgroup.Members.Add(jprofile);
+            return true;
+        }
+        return false;
+    }
+
+    public bool RemoveMember(Group group, UserProfile user)
+    {
+        if (group is JsonGroup jgroup && user is JsonUserProfile jprofile)
+        {
+            jgroup.Members.Remove(jprofile);
+            return true;
+        }
+        return false;
+    }
 }
diff --git a/OwnChar/Extensions.cs b/OwnChar/Extensions.cs
new file mode 100644
index 0000000..ee3bda6
--- /dev/null
+++ b/OwnChar/Extensions.cs
@@ -0,0 +1,11 @@
+using OwnChar.Model;
+
+namespace OwnChar;
+
+public static class Extensions
+{
+    public static bool HasPermission(this UserAccount account, UserType permissions)
+    {
+        return account.Type >= permissions;
+    }
+}
diff --git a/OwnChar/Manager/CharacterManager.cs b/OwnChar/Manager/CharacterManager.cs
index 501bdd9..568f7be 100644
--- a/OwnChar/Manager/CharacterManager.cs
+++ b/OwnChar/Manager/CharacterManager.cs
@@ -11,7 +11,7 @@ public class CharacterManager(OwnCharManager manager)
         Manager.CheckLogin();
 
         if (group != null)
-            return Manager.DataManager?.GetCharacters(group);
+            return Manager.DataManager?.GetCharacters(Manager.CurrentUser!, group);
 
         return null;
     }
@@ -21,8 +21,31 @@ public class CharacterManager(OwnCharManager manager)
         Manager.CheckLogin();
 
         if (profile != null)
-            return Manager.DataManager?.GetCharacters(profile);
+            return Manager.DataManager?.GetCharacters(Manager.CurrentUser!, profile);
 
         return null;
     }
+
+    public Character? CreateCharacter(string? name)
+    {
+        return CreateCharacter(name, null);
+    }
+
+    public Character? CreateCharacter(string? name, Group? destination)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(name, nameof(name));
+        
+        Manager.CheckLogin();
+
+        return Manager.DataManager?.CreateCharacter(Manager.CurrentUser!, name, destination);
+    }
+
+    public bool DeleteCharacter(Character? character)
+    {
+        ArgumentNullException.ThrowIfNull(character, nameof(character));
+
+        Manager.CheckLogin();
+
+        return Manager.DataManager?.DeleteCharacter(Manager.CurrentUser!, character) ?? false;
+    }
 }
diff --git a/OwnChar/Manager/GroupsManager.cs b/OwnChar/Manager/GroupsManager.cs
index d5287e6..eea146b 100644
--- a/OwnChar/Manager/GroupsManager.cs
+++ b/OwnChar/Manager/GroupsManager.cs
@@ -9,12 +9,42 @@ public class GroupsManager(OwnCharManager manager)
     public UserProfile? GetOwner(Group? group)
     {
         ArgumentNullException.ThrowIfNull(group, nameof(group));
-        return Manager.DataManager?.GetOwner(group);
+        return Manager.DataManager?.GetOwner(Manager.CurrentUser!, group);
     }
 
     public IEnumerable<UserProfile>? GetMembers(Group? group)
     {
         ArgumentNullException.ThrowIfNull(group, nameof(group));
-        return Manager.DataManager?.GetMembers(group);
+        return Manager.DataManager?.GetMembers(Manager.CurrentUser!, group);
+    }
+
+    public bool AddMember(UserProfile? profile, Group? group)
+    {
+        Manager.CheckLogin();
+        ArgumentNullException.ThrowIfNull(profile, nameof(profile));
+        ArgumentNullException.ThrowIfNull(group, nameof(group));
+        return Manager.DataManager?.AddMember(Manager.CurrentUser!, group, profile) ?? false;
+    }
+
+    public bool DeleteMember(UserProfile? profile, Group? group)
+    {
+        Manager.CheckLogin();
+        ArgumentNullException.ThrowIfNull(profile, nameof(profile));
+        ArgumentNullException.ThrowIfNull(group, nameof(group));
+        return Manager.DataManager?.RemoveMember(Manager.CurrentUser!, group, profile) ?? false;
+    }
+
+    public Group? CreateGroup(string? name)
+    {
+        Manager.CheckLogin();
+        ArgumentException.ThrowIfNullOrWhiteSpace(name, nameof(name));
+        return Manager.DataManager?.CreateGroup(Manager.CurrentUser!, name);
+    }
+
+    public bool DeleteGroup(Group? group)
+    {
+        Manager.CheckLogin();
+        ArgumentNullException.ThrowIfNull(group, nameof(group));
+        return Manager.DataManager?.DeleteGroup(Manager.CurrentUser!, group) ?? false;
     }
 }