They are claiming that DRB's blood was in the SM in part because his DNA was detected in the SM as well.
What are they basing this claim on?
Pamela Boutflour and Ann Eaton gave DNA samples in 2001. No record of DRB or RWB doing so.
The only way they could conceivably discover and prove this is if they managed to -
1. Convert the DNA info from both or either AE and PB into a raw CSV format.
2. Do the same for a DNA sample found in the moderator.
3. Upload the CSVs to GedMatch and it concludes the unknown DNA is from a sibling and or child of the other two profiles.