diff --git a/EnvelopeGenerator.Domain/Entities/DocumentStatus.cs b/EnvelopeGenerator.Domain/Entities/DocumentStatus.cs
index 3444475f..dd2feee1 100644
--- a/EnvelopeGenerator.Domain/Entities/DocumentStatus.cs
+++ b/EnvelopeGenerator.Domain/Entities/DocumentStatus.cs
@@ -1,5 +1,7 @@
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
+using EnvelopeGenerator.Domain.Interfaces;
+
 #if NETFRAMEWORK
 using System;
 #endif
@@ -12,7 +14,7 @@ namespace EnvelopeGenerator.Domain.Entities
 #endif
 
 [Table("TBSIG_DOCUMENT_STATUS", Schema = "dbo")]
-public class DocumentStatus
+public class DocumentStatus : IHasEnvelope, IHasReceiver
 {
     public DocumentStatus()
     {
@@ -43,10 +45,18 @@ public class DocumentStatus
     public string Value { get; set; }
 
     [ForeignKey("EnvelopeId")]
-    public virtual Envelope Envelope { get; set; }
+    public virtual Envelope
+#if NET
+        ?
+#endif
+        Envelope { get; set; }
 
     [ForeignKey("ReceiverId")]
-    public virtual Receiver Receiver { get; set; }
+    public virtual Receiver
+#if NET
+        ?
+#endif
+            Receiver { get; set; }
 }
 
 #if NETFRAMEWORK
diff --git a/EnvelopeGenerator.Domain/Entities/EnvelopeReceiver.cs b/EnvelopeGenerator.Domain/Entities/EnvelopeReceiver.cs
index 93cccaaa..cf3862f3 100644
--- a/EnvelopeGenerator.Domain/Entities/EnvelopeReceiver.cs
+++ b/EnvelopeGenerator.Domain/Entities/EnvelopeReceiver.cs
@@ -1,6 +1,7 @@
 using System.ComponentModel.DataAnnotations;
 using System.ComponentModel.DataAnnotations.Schema;
-using System.Drawing;
+using EnvelopeGenerator.Domain.Interfaces;
+
 #if NETFRAMEWORK
 using System;
 #endif
@@ -13,7 +14,7 @@ namespace EnvelopeGenerator.Domain.Entities
 #endif
 
 [Table("TBSIG_ENVELOPE_RECEIVER", Schema = "dbo")]
-public class EnvelopeReceiver
+public class EnvelopeReceiver : IHasEnvelope, IHasReceiver
 {
     public EnvelopeReceiver()
     {
@@ -70,10 +71,18 @@ public class EnvelopeReceiver
     public bool HasPhoneNumber => !string.IsNullOrWhiteSpace(PhoneNumber);
 
     [ForeignKey("EnvelopeId")]
-    public Envelope Envelope { get; set; }
+    public Envelope
+#if NET
+        ?
+#endif
+            Envelope { get; set; }
 
     [ForeignKey("ReceiverId")]
-    public Receiver Receiver { get; set; }
+    public Receiver
+#if NET
+        ?
+#endif
+            Receiver { get; set; }
 
     #region Model of old serice
     [NotMapped]
@@ -86,8 +95,8 @@ public class EnvelopeReceiver
     public bool HasEmailAndName =>
         !string.IsNullOrWhiteSpace(Receiver.EmailAddress) &&
         !string.IsNullOrWhiteSpace(Name);
-    #endregion
-}
+        #endregion
+    }
 
 #if NETFRAMEWORK
     }
diff --git a/EnvelopeGenerator.Domain/Interfaces/IHasEnvelope.cs b/EnvelopeGenerator.Domain/Interfaces/IHasEnvelope.cs
new file mode 100644
index 00000000..bfc38712
--- /dev/null
+++ b/EnvelopeGenerator.Domain/Interfaces/IHasEnvelope.cs
@@ -0,0 +1,22 @@
+namespace EnvelopeGenerator.Domain.Interfaces
+#if NET
+    ;
+#elif NETFRAMEWORK
+    {
+#endif
+
+interface IHasEnvelope
+{
+#if NET
+    public 
+#endif
+        Entities.Envelope
+#if NET
+        ?
+#endif
+            Envelope { get; set; }
+}
+
+#if NETFRAMEWORK
+}
+#endif
\ No newline at end of file
diff --git a/EnvelopeGenerator.Domain/Interfaces/IHasReceiver.cs b/EnvelopeGenerator.Domain/Interfaces/IHasReceiver.cs
new file mode 100644
index 00000000..d14c9ca6
--- /dev/null
+++ b/EnvelopeGenerator.Domain/Interfaces/IHasReceiver.cs
@@ -0,0 +1,22 @@
+namespace EnvelopeGenerator.Domain.Interfaces
+#if NET
+    ;
+#elif NETFRAMEWORK
+    {
+#endif
+
+interface IHasReceiver
+    {
+#if NET
+    public 
+#endif
+        Entities.Receiver
+#if NET
+        ?
+#endif
+            Receiver { get; set; }
+}
+
+#if NETFRAMEWORK
+}
+#endif
\ No newline at end of file