diff --git a/EXE_GdbCreateSurf.cpp b/EXE_GdbCreateSurf.cpp
index 117f1b4..9d5720f 100644
--- a/EXE_GdbCreateSurf.cpp
+++ b/EXE_GdbCreateSurf.cpp
@@ -3096,7 +3096,7 @@ ExeCreateSurfExtensionFromMany( int nParentId, const INTVECTOR& vSurfId, double
       if ( pnCount != nullptr)
          ++ *pnCount ;
    }
-   if ( bDrawOffEdge  &&  pOffEdge->IsValid()) {
+   if ( bDrawOffEdge  &&  pOffEdge != nullptr  &&  pOffEdge->IsValid()) {
       int nEdgeId = pGeomDB->AddGeoObj( GDB_ID_NULL, nParentId, pOffEdge) ;
       if ( nEdgeId != GDB_ID_NULL) {
          if ( pnCount != nullptr)
diff --git a/EXE_Trimming.cpp b/EXE_Trimming.cpp
index 7688b52..4bf8442 100644
--- a/EXE_Trimming.cpp
+++ b/EXE_Trimming.cpp
@@ -649,7 +649,7 @@ ExeTrimmingGetRuledBezier( int nParentId, const INTVECTOR& vIds, int nEdge1Id, i
 // ---------------------------------------------------------------------------
 bool
 ExeTrimmingInterpolateSyncLines( int nParentId, int nSync1Id, int nSync2Id, int nBorder1Id,
-                                 int nBorder2Id, double dEdgeLinTol, double dEdgeAngTol,
+                                 int nBorder2Id, double dEdgeLinTol, double dEdgeAngTol, bool bShorterSide, bool bEraseOrigLines,
                                  int& nFirstId, int& nCount)
 {
   // Verifica database geometrico
@@ -678,9 +678,41 @@ ExeTrimmingInterpolateSyncLines( int nParentId, int nSync1Id, int nSync2Id, int
 
   // Calcolo le Curve di sincornizzazione Interpolate
    BIPNTVECTOR vSyncPoints ;
+   GuideBounds gbGuideBounds ;
    bOk = bOk && GetTrimmingSyncInterpolation( pCrvEdge1, pCrvEdge2, pSync1, pSync2, dMyEdgeLinTol,
-                                              dMyEdgeAngTol, vSyncPoints) ;
+                                              dMyEdgeAngTol, bShorterSide, vSyncPoints, gbGuideBounds) ;
    if ( bOk  &&  ! vSyncPoints.empty()) {
+      if ( bEraseOrigLines) {
+         // scorro tutte le curve si sync già presenti e le elimino se entro i limiti della zona di interpolazione
+         int nSyncId = pGeomDB->GetFirstInGroup( nParentId) ;
+         while ( nSyncId != GDB_ID_NULL) {
+            double dS, dE ;
+            Point3d ptStart, ptEnd ;
+            ICurve* pSync = GetCurve( pGeomDB->GetGeoObj( nSyncId)) ;
+            pSync->GetStartPoint( ptStart) ;
+            pSync->GetEndPoint( ptEnd) ;
+            if ( ! pCrvEdge1->GetParamAtPoint( ptStart, dS, dMyEdgeLinTol)) {
+               pSync->Invert() ;
+               swap( ptStart, ptEnd) ;
+               if ( ! pCrvEdge1->GetParamAtPoint( ptStart, dS, dMyEdgeLinTol)) {
+                  pSync->Invert() ;
+                  bOk = false ;
+                  break ;
+               }
+            }
+            if ( ! pCrvEdge2->GetParamAtPoint( ptEnd, dE, dMyEdgeLinTol)) {
+               bOk = false ;
+               break ;
+            }
+            int nCurrId = nSyncId ;
+            nSyncId = pGeomDB->GetNext( nSyncId) ;
+            if ( ( gbGuideBounds.bDirect  &&
+                 (( dS > gbGuideBounds.dS1  &&  dS < gbGuideBounds.dE1)  ||  ( dE > gbGuideBounds.dS2  &&  dE < gbGuideBounds.dE2)))  ||
+                 ( ! gbGuideBounds.bDirect  &&
+                 (( dS < gbGuideBounds.dS1  ||  dS > gbGuideBounds.dE1)  ||  ( dE < gbGuideBounds.dS2  ||  dE > gbGuideBounds.dE2))))
+               pGeomDB->Erase( nCurrId) ;
+         }
+      }
      // Inserisco le curve di sincronizzazione nel DB
      // [orientate da pCrvEdge1 a pCrvEdge2]
       for ( int i = 0 ; bOk && i < ssize( vSyncPoints) ; ++ i) {
diff --git a/EgtExecutor.rc b/EgtExecutor.rc
index 54ef07b..b1a85cd 100644
Binary files a/EgtExecutor.rc and b/EgtExecutor.rc differ
diff --git a/Lua_Trimming.cpp b/Lua_Trimming.cpp
index 31d13dd..e1af756 100644
--- a/Lua_Trimming.cpp
+++ b/Lua_Trimming.cpp
@@ -226,7 +226,7 @@ LuaTrimmingGetRuledBezier( lua_State* L)
 static int
 LuaTrimmingInterpolateSyncLines( lua_State* L)
 {
-  // 7 parametri : nParentId, nFirstSyncId, nSecondSyncId, nBorder1Id, nBorder2Id, dEdgeLinTol, dEdgeAngTol
+  // 9 parametri : nParentId, nFirstSyncId, nSecondSyncId, nBorder1Id, nBorder2Id, dEdgeLinTol, dEdgeAngTol, bShorterSide, bEraseOrigLines
    int nParentId ;
    LuaCheckParam( L, 1, nParentId) ;
    int nSync1Id ;
@@ -241,12 +241,16 @@ LuaTrimmingInterpolateSyncLines( lua_State* L)
    LuaCheckParam( L, 6, dEdgeLinTol) ;
    double dEdgeAngTol ;
    LuaCheckParam( L, 7, dEdgeAngTol) ;
+   bool bShorterSide = true ;
+   LuaCheckParam( L, 8, bShorterSide) ;
+   bool bEraseOrigLines = true ;
+   LuaCheckParam( L, 9, bEraseOrigLines) ;
    LuaClearStack( L) ;
   // Interpolo le curve di sincronizzazione
    int nFirstId = GDB_ID_NULL ;
    int nCount = 0 ;
    bool bOk = ExeTrimmingInterpolateSyncLines( nParentId, nSync1Id, nSync2Id, nBorder1Id,
-                                               nBorder2Id, dEdgeLinTol, dEdgeAngTol, nFirstId, nCount) ;
+                                               nBorder2Id, dEdgeLinTol, dEdgeAngTol, bShorterSide, bEraseOrigLines, nFirstId, nCount) ;
    LuaSetParam( L, bOk) ;
    LuaSetParam( L, nFirstId) ;
    LuaSetParam( L, nCount) ;