Macro: Add a custom property & link it to a current custom property

I have a assembly package i need to add/update some variables...

Generally i would run a macro to add the variables using...

AddCustProp "---", swCustomInfoType_e.swCustomInfoText, "---"

But now i want to link a new variable to an existing one.

Example. My current variable is "DRAWNBY",  my new end customer is "NAME OF DESIGNER".  I want to link their "NAME OF DESIGNER" variable to my original "DRAWNBY" variable.

Manually in the property manager i can just add \$PRP:"DRAWNBY" & it works, but not in the macro.

Whats can i do it through this method, what would be a way to accomplish it...did i miss anything?

SolidworksApi macros