Adobe Campaign Classic Control Groups in Delivery

Hello, the targeted audience going into the delivery activity has multiple segment codes. For example, 100 people with 50% segment code A and 50% segment code B. I'd like to have a control group of 20% for EACH segment. So of the 50 people labeled segment code A, we'd like to have 20% in control group (10 people), and of the 50 people labeled segment code B, we'd also like to have 20% in control group (10 people). Total send would be 80 recipients (40 from each segment code) and 20 recipients in the control group (10 from each segment code). Is this possible to do in one delivery? My only other thought is to do a split for each segment (random sample of 20%) and give them a label of "control" in the target data and then in the delivery control group configuration select anyone with the label of "control". I'm trying to avoid reworking the workflow to add in the splits for each segment and then union everything back together again to input into the delivery. Thank you in advance for any help!! Cindy