Multiple Custom Properties into Variable

All -

I'm trying to figure out how to parse multiple custom properties into (1) PDM Standard variable. For example I have custom properties within a SW part file called:

CATEGORY

DESCRIPTION

PURCHASED-CAT

SUB-CATEGORY

VENDOR

VENDOR PART NUMBER

PURCHASED-DESC

CATEGORY DESCRIPTION

PURCHASED-CAT SUB-CATEGORY VENDOR VENDOR PART NUMBER PURCHASED-DESC

The kicker is the fact that not all of these custom properties are always filled out. I have grouped them into (2) different sets showing the string breakout that I am looking for. I would like to parse these properties into a variable called "BOM DESCRIPTION" How could I go about getting this working? I tried using the CustomProperty attribute but that would only parse a single custom property, whereas I'm trying to combine multiple ones.

Screenshot 2017-09-20 11.20.27.png

Any help here would be greatly appreciated!