code: private static void hideMultipleParts(IAtomContainer container, Sgroup sgroup) {
  
          final Set<IBond> crossing = sgroup.getBonds();
          final Set<IAtom> atoms = sgroup.getAtoms();
          final Set<IAtom> parentAtoms = sgroup.getValue(SgroupKey.CtabParentAtomList);
  
          for (IBond bond : container.bonds()) {
              if (parentAtoms.contains(bond.getBegin()) && parentAtoms.contains(bond.getEnd()))
                  continue;
              if (atoms.contains(bond.getBegin()) || atoms.contains(bond.getEnd()))
                  StandardGenerator.hide(bond);
          }
          for (IAtom atom : atoms) {
              if (!parentAtoms.contains(atom))
                  StandardGenerator.hide(atom);
          }
          for (IBond bond : crossing) {
              StandardGenerator.unhide(bond);
          }
      }
docs: Hide the repeated atoms and bonds of a multiple group. We hide al atoms that
  belong to the group unless they are defined in the parent atom list. Any
  bond to those atoms that is not a crossing bond or one connecting atoms in
  the parent list is hidden.
  
  @param container molecule
  @param sgroup    multiple group display shortcut