Hierarchical design in Isis Proteus
From answer posted here
It's in the Proteus Help file:

SCHEMATIC CAPTURE HELP (F1) -> MULTI-SHEET DESIGNS -> Hierarchical Designs

See the section "Module Components":


  Any ordinary component can be made into a module by setting the Attach Hierarchy Module checkbox on the Edit Component dialogue form.
  The component's value is taken to be the name for the associated circuit,
  and the component's reference serves as the instance name.


after this you can use your new implementation of that component with your new name. for making it available at library see "External Modules" section of proteus help.