How do you manage WIP quantities on quality hold?

I am curious to learn how other companies are handling WIP quantities on quality hold.

Our scenario is: manufacturing work orders with multi-step routings. We may have a 10-step routing with quantities at operation #4, say 10,000 ea. 2,000 of those are suspect and the quality department would like to pull those off the manufacturing line in order to perform more inspections/testing on them. We have not figured out a good way to systemically indicate that those 2,000 ea are on a quality hold. There are no lot numbers or inventory because these quantities are in WIP, so we can't put lot numbers on a hold status.