diff --git a/EgtBEAMWALL.DataLayer/Controllers/ProjController.cs b/EgtBEAMWALL.DataLayer/Controllers/ProjController.cs
index 1bb404a6..aa53f68a 100644
--- a/EgtBEAMWALL.DataLayer/Controllers/ProjController.cs
+++ b/EgtBEAMWALL.DataLayer/Controllers/ProjController.cs
@@ -383,49 +383,65 @@ namespace EgtBEAMWALL.DataLayer.Controllers
         /// <returns></returns>
         public ProjModel UpdateBtlParts(int ProjId, List<Core.BTLPartM> BtlPartList)
         {
+            // record del proj corrente
             var currData = FindByProjId(ProjId);
 
-            // 2021.05.03 modifica update: esistenti le MODIFICO
+            // 2021.05.03 modifica update: esistenti le MODIFICO, nuove aggiungo, inesistenti elimino in cascata con Part
 
-            // sel delle BTLParts da proj
+            // sel delle BTLParts del proj
             List<BTLPartModel> oldBtlParts = dbCtx
                 .BTLPartList
                 .Where(x => x.ProjDbId == currData.ProjDbId)
                 .ToList();
 
-            // converto le BtlParts
+            // converto le BtlParts da core --> DB
             List<BTLPartModel> newBtlParts = BtlPartList.Select(x => BTLPartController.ConvertFromCore(x, currData.ProjDbId)).ToList();
 
             try
             {
-                // elementi NON + presenti da eliminare
-                var old2rem = oldBtlParts.Except(newBtlParts).ToList();
-                var new2Add = newBtlParts.Except(oldBtlParts).ToList();
-                var existing = oldBtlParts.Except(old2rem).ToList();
-                var newOnes = new2Add.Except(new2Add).ToList();
+                // elementi BtlPartId NON + presenti da eliminare
+                List<int> bpi2rem = oldBtlParts.Select(x => x.PartId).Except(newBtlParts.Select(y => y.PartId)).ToList();
+                List<int> bpi2add = newBtlParts.Select(x => x.PartId).Except(oldBtlParts.Select(y => y.PartId)).ToList();
+                List<int> bpiExis = newBtlParts.Select(x => x.PartId).Intersect(oldBtlParts.Select(y => y.PartId)).ToList();
+
                 // aggiorno existing...
-                foreach (var item in existing)
+                foreach (var currPartId in bpiExis)
                 {
-                    // recupero nuovo item...
-                    var newItem = newOnes.Where(x => x.PartId == item.PartId).FirstOrDefault();
-                    if (newItem != null)
+                    // recupero item da aggiornare...
+                    var oldItem = oldBtlParts.Where(x => x.PartId == currPartId).FirstOrDefault();
+                    // dati nuovo item
+                    var newItem = newBtlParts.Where(x => x.PartId == currPartId).FirstOrDefault();
+                    if (newItem != null && oldItem != null)
                     {
-                        item.CALC_State = newItem.CALC_State;
-                        item.CNT = newItem.CNT;
-                        item.DO = newItem.DO;
-                        item.H = newItem.H;
-                        item.L = newItem.L;
-                        item.W = newItem.W;
-                        item.Material = newItem.Material;
-                        item.NAM = newItem.NAM;
-                        item.PDN = newItem.PDN;
+                        oldItem.CALC_State = newItem.CALC_State;
+                        oldItem.CNT = newItem.CNT;
+                        oldItem.DO = newItem.DO;
+                        oldItem.H = newItem.H;
+                        oldItem.L = newItem.L;
+                        oldItem.W = newItem.W;
+                        oldItem.Material = newItem.Material;
+                        oldItem.NAM = newItem.NAM;
+                        oldItem.PDN = newItem.PDN;
                     }
                 }
 
+                // aggiungo le nuove part
+                foreach (var newPartId in bpi2add)
+                {
+                    var newItem = newBtlParts.Where(x => x.PartId == newPartId).FirstOrDefault();
+                    dbCtx.BTLPartList.Add(newItem);
+                }
+
                 // elimino dal DB i non + esistenti
-                dbCtx.BTLPartList.RemoveRange(old2rem);
-                // aggiungo le nuove
-                dbCtx.BTLPartList.AddRange(new2Add);
+                foreach (var oldPartId in bpi2rem)
+                {
+                    // elimino parts nei MachGroup
+                    var oldIstPartList = dbCtx.PartList.Where(x => x.BTLPart.PartId == oldPartId).ToList();
+                    dbCtx.PartList.RemoveRange(oldIstPartList);
+                    // elimino BtlParts
+                    var oldItem = oldBtlParts.Where(x => x.PartId == oldPartId).FirstOrDefault();
+                    dbCtx.BTLPartList.Remove(oldItem);
+                }
             }
             catch
             { }
diff --git a/EgtBEAMWALL.DataLayer/EgtBEAMWALL.DataLayer.csproj b/EgtBEAMWALL.DataLayer/EgtBEAMWALL.DataLayer.csproj
index c8740662..82b1cb34 100644
--- a/EgtBEAMWALL.DataLayer/EgtBEAMWALL.DataLayer.csproj
+++ b/EgtBEAMWALL.DataLayer/EgtBEAMWALL.DataLayer.csproj
@@ -53,6 +53,9 @@
     <Reference Include="MySql.Data.Entity.EF6, Version=6.10.9.0, Culture=neutral, PublicKeyToken=c5687fc88969c44d, processorArchitecture=MSIL">
       <HintPath>..\packages\MySql.Data.Entity.6.10.9\lib\net452\MySql.Data.Entity.EF6.dll</HintPath>
     </Reference>
+    <Reference Include="Newtonsoft.Json, Version=13.0.0.0, Culture=neutral, PublicKeyToken=30ad4fe6b2a6aeed, processorArchitecture=MSIL">
+      <HintPath>..\packages\Newtonsoft.Json.13.0.1\lib\net45\Newtonsoft.Json.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.ComponentModel" />
     <Reference Include="System.ComponentModel.DataAnnotations" />
@@ -108,6 +111,7 @@
     </Compile>
     <Compile Include="Migrations\Configuration.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="Utils.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="App.config" />
diff --git a/EgtBEAMWALL.DataLayer/Utils.cs b/EgtBEAMWALL.DataLayer/Utils.cs
new file mode 100644
index 00000000..87bb6af8
--- /dev/null
+++ b/EgtBEAMWALL.DataLayer/Utils.cs
@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace EgtBEAMWALL.DataLayer
+{
+    public static partial class LinqExtensions
+    {
+        #region Public Methods
+
+        public static IEnumerable<T> ExceptUsingJSonCompare<T>
+            (this IEnumerable<T> first, IEnumerable<T> second)
+        {
+            return first.Except(second, new JSonEqualityComparer<T>());
+        }
+
+        #endregion Public Methods
+    }
+
+    /// <summary>
+    /// Comparer generico basato su Json
+    /// https://stackoverflow.com/questions/7042090/linq-except-with-custom-iequalitycomparer/7098076#7098076
+    /// </summary>
+    /// <typeparam name="T"></typeparam>
+    public class JSonEqualityComparer<T> : IEqualityComparer<T>
+    {
+        #region Public Methods
+
+        public bool Equals(T x, T y)
+        {
+            return String.Equals
+            (
+                Newtonsoft.Json.JsonConvert.SerializeObject(x),
+                Newtonsoft.Json.JsonConvert.SerializeObject(y)
+            );
+        }
+
+        public int GetHashCode(T obj)
+        {
+            return Newtonsoft.Json.JsonConvert.SerializeObject(obj).GetHashCode();
+        }
+
+        #endregion Public Methods
+    }
+}
\ No newline at end of file
diff --git a/EgtBEAMWALL.DataLayer/packages.config b/EgtBEAMWALL.DataLayer/packages.config
index ffa9838d..1206a06d 100644
--- a/EgtBEAMWALL.DataLayer/packages.config
+++ b/EgtBEAMWALL.DataLayer/packages.config
@@ -3,4 +3,5 @@
   <package id="EntityFramework" version="6.4.4" targetFramework="net452" />
   <package id="MySql.Data" version="6.10.9" targetFramework="net452" />
   <package id="MySql.Data.Entity" version="6.10.9" targetFramework="net452" />
+  <package id="Newtonsoft.Json" version="13.0.1" targetFramework="net452" />
 </packages>
\ No newline at end of file