Mirror Part - Append to Linked Custom Properties

Before we did the switch to SW 2010 we had a macro that we would run on our mirror parts which would open the non-mirror part and retrieve all the custom properties, then insert them into the mirror part and append where needed (ie: partdescription "- Mirror").  The problem is that this is not a dynamic link and the macro has to be run with any change to the custom properties.

In 2010 we see that we can link custom properties to the non-mirror part however I have not been able to successfully append to a linked custom property.  Does anyone know if there is a way to append to linked custom properties, ideally though a macro.

SolidworksApi macros