Insert new Custom Properties into old files

Can someone quickly let me know if there is a way to add newCustom Property names (with their values) into old files.

We are upgrading a lot of templates and need to add new propertiesto old files. The new properties are \$PRP and \$PRPSHEET formatted....

Want to see if I can make it easier for the engineers needing toupdate everything.

Thanks.SolidworksApi macros