dispatch scripts that could append existing string

I have created a few dispatch scripts that adds a unique agency certificate number to a variable field; what I'm finding now is that this particular field could have more than one of these certificate numbers.  There could be infinate combinations, so creating multiple scripts would be be suck.  I do not want to overwrite what is already there, so I was wondering if anyone knows a syntaxt that would allow me to append a string of text.

or does anyone have another possible solution.

-Rick

SolidworksApi macros