Ok, I'm using Proteus 8.8 SP1 and I have created a subcircuit, which is basically a linear power supply. Then I have made two copies of this subcircuit.
First strange thing: The subcircuit copies haven't received a new reference, and are still showing up as SUB1. When I copy a single component, like a cap, Proteus gives it a new reference, but this isn't happening with a subcircuit.
Oh well, so I went ahead and changed the references of the copies to SUB2 and SUB3. Then I entered the schematic of SUB1 and made a modification.
Second MAJOR strange thing: The change I have made was not reflected in SUB2 and SUB3!!! This doesn't make any sense to me at all. This completely defeats the purpose of having subcircuits.
I hope I'm doing something wrong and this isn't by design. But if it is by design, then I don't know how this feature can be effectively used. Imagine using subcircuits to build a stereo amp. If you have made 10 mods to the LEFT subcircuit, you have to make the same modifications to the RIGHT channel.