diff --git a/src/SIM/SIM2D.C b/src/SIM/SIM2D.C
index baa1fe33..ca05d49f 100644
--- a/src/SIM/SIM2D.C
+++ b/src/SIM/SIM2D.C
@@ -68,6 +68,45 @@ SIM2D::SIM2D (IntegrandBase* itg, unsigned char n, bool check) : SIMgeneric(itg)
 }
 
 
+bool SIM2D::addConnection (int master, int slave, int mIdx,
+                           int sIdx, int orient, int basis, bool coordCheck)
+{
+  if (orient < 0 || orient > 1) {
+    std::cerr <<" *** SIM2D::addConnection: Invalid orientation "<< orient <<"."
+              << std::endl;
+    return false;
+  }
+
+  int lmaster = this->getLocalPatchIndex(master);
+  int lslave = this->getLocalPatchIndex(slave);
+
+  if (lmaster > 0 && lslave > 0)
+  {
+    IFEM::cout <<"\tConnecting P"<< slave <<" E"<< sIdx
+               <<" to P"<< master <<" E"<< mIdx
+               <<" reversed? "<< orient << std::endl;
+
+    ASMs2D* spch = static_cast<ASMs2D*>(myModel[lslave-1]);
+    ASMs2D* mpch = static_cast<ASMs2D*>(myModel[lmaster-1]);
+
+    std::set<int> bases;
+    if (basis == 0)
+      for (size_t b = 1; b <= spch->getNoBasis(); ++b)
+        bases.insert(b);
+    else
+      bases = utl::getDigits(basis);
+
+    for (const int& b : bases)
+      if (!spch->connectPatch(sIdx,*mpch,mIdx,orient,b,coordCheck))
+        return false;
+  }
+  else
+    adm.dd.ghostConnections.insert(DomainDecomposition::Interface{master, slave, mIdx, sIdx, orient, 1});
+
+  return true;
+}
+
+
 bool SIM2D::parseGeometryTag (const TiXmlElement* elem)
 {
   IFEM::cout <<"  Parsing <"<< elem->Value() <<">"<< std::endl;
@@ -157,13 +196,19 @@ bool SIM2D::parseGeometryTag (const TiXmlElement* elem)
     const TiXmlElement* child = elem->FirstChildElement("connection");
     for (; child; child = child->NextSiblingElement())
     {
-      int master = 0, slave = 0, mEdge = 0, sEdge = 0;
-      bool rever = false;
+      int master = 0, slave = 0, mEdge = 0, sEdge = 0, orient = 0, basis = 0;
+      bool rever = false, periodic = false;
       utl::getAttribute(child,"master",master);
-      utl::getAttribute(child,"medge",mEdge);
+      if (!utl::getAttribute(child,"midx",mEdge))
+        utl::getAttribute(child,"medge",mEdge);
       utl::getAttribute(child,"slave",slave);
-      utl::getAttribute(child,"sedge",sEdge);
-      utl::getAttribute(child,"reverse",rever);
+      if (!utl::getAttribute(child,"sidx",sEdge))
+        utl::getAttribute(child,"sedge",sEdge);
+      if (!utl::getAttribute(child,"orient",orient))
+        if (utl::getAttribute(child,"reverse",rever) && rever)
+          orient = 1;
+      utl::getAttribute(child,"basis",basis);
+      utl::getAttribute(child,"periodic",periodic);
 
       if (master == slave ||
           master < 1 || master > nGlPatches ||
@@ -173,24 +218,17 @@ bool SIM2D::parseGeometryTag (const TiXmlElement* elem)
                   << master <<" "<< slave << std::endl;
         return false;
       }
-      int lmaster = this->getLocalPatchIndex(master);
-      int lslave = this->getLocalPatchIndex(slave);
 
-      if (lmaster > 0 && lslave > 0)
+      if (!this->addConnection(master,slave,mEdge,sEdge,orient,basis,!periodic))
       {
-        IFEM::cout <<"\tConnecting P"<< lslave <<" E"<< sEdge
-                   <<" to P"<< lmaster <<" E"<< mEdge
-                   <<" reversed? "<< rever << std::endl;
-        ASMs2D* spch = static_cast<ASMs2D*>(myModel[lslave-1]);
-        ASMs2D* mpch = static_cast<ASMs2D*>(myModel[lmaster-1]);
-        if (!spch->connectPatch(sEdge,*mpch,mEdge,rever))
-          return false;
-        else if (opt.discretization == ASM::SplineC1)
-          top.push_back(Interface(static_cast<ASMs2DC1*>(mpch),mEdge,
-                                  static_cast<ASMs2DC1*>(spch),sEdge,rever));
+        std::cerr <<" *** SIM2D::parse: Error establishing connection."
+                  << std::endl;
+        return false;
       }
-      else
-        adm.dd.ghostConnections.insert(DomainDecomposition::Interface{master, slave, mEdge, sEdge, rever?1:0, 1});
+
+      if (opt.discretization == ASM::SplineC1)
+        top.push_back(Interface(static_cast<ASMs2DC1*>(this->getPatch(master,true)),mEdge,
+                                static_cast<ASMs2DC1*>(this->getPatch(slave,true)),sEdge,orient));
     }
 
     // Second pass for C1-continuous patches, to set up additional constraints
diff --git a/src/SIM/SIM2D.h b/src/SIM/SIM2D.h
index 98e303aa..c35b4de0 100644
--- a/src/SIM/SIM2D.h
+++ b/src/SIM/SIM2D.h
@@ -70,6 +70,17 @@ public:
   virtual bool readPatches(std::istream& isp, PatchVec& patches,
                            const char* whiteSpace) const;
 
+  //! \brief Connect two patches.
+  //! \param master Master patch
+  //! \param slave Slave patch
+  //! \param mEdge Edge on master
+  //! \param sEdge Edge on slave
+  //! \param orient Orientation flag for connection (1 for reversed)
+  //! \param basis Which bases to connect (0 for all)
+  //! \param coordCheck False to turn off coordinate checks
+  bool addConnection(int master, int slave, int mEdge, int sEdge,
+                     int orient, int basis = 0, bool coordCheck = true);
+
   //! \brief Evaluates the primary solution at the given point.
   //! \param[in] psol Primary solution vector
   //! \param[in] u First parameter of the point to evaluate at
diff --git a/src/SIM/SIM3D.C b/src/SIM/SIM3D.C
index 4f857316..aa864385 100644
--- a/src/SIM/SIM3D.C
+++ b/src/SIM/SIM3D.C
@@ -46,6 +46,44 @@ SIM3D::SIM3D (IntegrandBase* itg, unsigned char n, bool check) : SIMgeneric(itg)
 }
 
 
+bool SIM3D::addConnection (int master, int slave, int mIdx,
+                           int sIdx, int orient, int basis, bool coordCheck)
+{
+  if (orient < 0 || orient > 7) {
+    std::cerr <<" *** SIM3D::addConnection: Invalid orientation "<< orient <<"."
+              << std::endl;
+    return false;
+  }
+
+  int lmaster = this->getLocalPatchIndex(master);
+  int lslave = this->getLocalPatchIndex(slave);
+  if (lmaster > 0 && lslave > 0)
+  {
+    IFEM::cout <<"\tConnecting P"<< slave <<" F"<< sIdx
+               <<" to P"<< master <<" F"<< mIdx
+               <<" orient "<< orient << std::endl;
+
+    ASMs3D* spch = static_cast<ASMs3D*>(myModel[lslave-1]);
+    ASMs3D* mpch = static_cast<ASMs3D*>(myModel[lmaster-1]);
+
+    std::set<int> bases;
+    if (basis == 0)
+      for (size_t b = 1; b <= spch->getNoBasis(); ++b)
+        bases.insert(b);
+    else
+      bases = utl::getDigits(basis);
+
+    for (const int& b : bases)
+      if (!spch->connectPatch(sIdx,*mpch,mIdx,orient,b,coordCheck))
+        return false;
+  }
+  else
+    adm.dd.ghostConnections.insert(DomainDecomposition::Interface{master, slave, mIdx, sIdx, orient, 2});
+
+  return true;
+}
+
+
 bool SIM3D::parseGeometryTag (const TiXmlElement* elem)
 {
   IFEM::cout <<"  Parsing <"<< elem->Value() <<">"<< std::endl;
@@ -138,12 +176,15 @@ bool SIM3D::parseGeometryTag (const TiXmlElement* elem)
     const TiXmlElement* child = elem->FirstChildElement("connection");
     for (; child; child = child->NextSiblingElement())
     {
-      int master = 0, slave = 0, mFace = 0, sFace = 0, orient = 0;
+      int master = 0, slave = 0, mFace = 0, sFace = 0, orient = 0, basis = 0;
+      bool periodic = false;
       utl::getAttribute(child,"master",master);
       utl::getAttribute(child,"mface",mFace);
       utl::getAttribute(child,"slave",slave);
       utl::getAttribute(child,"sface",sFace);
       utl::getAttribute(child,"orient",orient);
+      utl::getAttribute(child,"basis",basis);
+      utl::getAttribute(child,"periodic",periodic);
 
       if (master == slave ||
           master < 1 || master > nGlPatches ||
@@ -153,18 +194,14 @@ bool SIM3D::parseGeometryTag (const TiXmlElement* elem)
                   << master <<" "<< slave << std::endl;
         return false;
       }
-      int lmaster = this->getLocalPatchIndex(master);
-      int lslave = this->getLocalPatchIndex(slave);
-      if (lmaster > 0 && lslave > 0) {
-        IFEM::cout <<"\tConnecting P"<< lslave <<" F"<< sFace
-                   <<" to P"<< lmaster <<" F"<< mFace
-                   <<" orient "<< orient << std::endl;
-        ASMs3D* spch = static_cast<ASMs3D*>(myModel[lslave-1]);
-        ASMs3D* mpch = static_cast<ASMs3D*>(myModel[lmaster-1]);
-        if (!spch->connectPatch(sFace,*mpch,mFace,orient))
-          return false;
-      } else
-        adm.dd.ghostConnections.insert(DomainDecomposition::Interface{master, slave, mFace, sFace, orient, 2});
+
+      if (!this->addConnection(master, slave, mFace, sFace,
+                               orient, basis, !periodic))
+      {
+        std::cerr <<" *** SIM3D::parse: Error establishing connection."
+                  << std::endl;
+        return false;
+      }
     }
   }
 
diff --git a/src/SIM/SIM3D.h b/src/SIM/SIM3D.h
index df9aeaeb..9cbebb8f 100644
--- a/src/SIM/SIM3D.h
+++ b/src/SIM/SIM3D.h
@@ -65,6 +65,17 @@ public:
   virtual bool readPatches(std::istream& isp, PatchVec& patches,
                            const char* whiteSpace) const;
 
+  //! \brief Connect two patches.
+  //! \param master Master patch
+  //! \param slave Slave patch
+  //! \param mFace Face on master
+  //! \param sFace Face on slave
+  //! \param orient Orientation flag for connection
+  //! \param basis Which bases to connect (0 for all)
+  //! \param coordCheck False to turn off coordinate checks
+  bool addConnection(int master, int slave, int mFace, int sFace,
+                     int orient, int basis = 0, bool coordCheck = true);
+
   //! \brief Evaluates the primary solution at the given point.
   //! \param[in] psol Primary solution vector
   //! \param[in] u First parameter of the point to evaluate at
diff --git a/src/SIM/SIMbase.h b/src/SIM/SIMbase.h
index 84cb50fa..c61f5723 100644
--- a/src/SIM/SIMbase.h
+++ b/src/SIM/SIMbase.h
@@ -91,6 +91,18 @@ public:
   //! \brief Returns a list of prioritized XML-tags.
   virtual const char** getPrioritizedTags() const;
 
+  //! \brief Connect two patches.
+  //! \param master Master patch
+  //! \param slave Slave patch
+  //! \param mIdx Index on master
+  //! \param sIdx Index on slave
+  //! \param orient Orientation flag
+  //! \param basis Which bases to connect (0 for all)
+  //! \param coordCheck False to turn off coordinate checks.
+  virtual bool addConnection(int master, int slave, int mIdx, int sIdx,
+                             int orient, int basis = 0, bool coordCheck = true)
+  { return false; }
+
 protected:
   //! \brief Parses the "set" attribute of a material XML-tag.
   //! \param[in] elem The XML element extract the set name from