I did mine as an additional tab in my HA, but basically rated things the same, risk/severity of impact of foreign materials, etc.. That's not to say how I did it is how everyone should, but my auditor accepted what I did. But to me it's a little different than the HA, so I kind of made it its own thing. Just look at your operation, what foreign material risks you have in your building, and run them through that sort of matrix, and judging by your scores, you'll know if you're ok as is, or if you need to make adjustments.