I have another division of our company, sent me a few thousand files.  I'm going through them & they are all are missing some needed Custom Properties.  Anyone have a Snip-it of code or a macro that checks to see if a model has a custom property, if so "skip it", if not add it (just the property, value will be blank).  I have a macro that completely deletes all properties and reloads a new set.  But i don't want to delete the already present properties.

As always all help is appreciated