Why not fly UA/SAS BVT-ORD-ARN-ORD-BVT on one ticket with one set of baggage rules?
Edit: Just realised that you may be planning a stopover in London, so my suggestion wouldn't work.
Try CO BVT-EWR-xLHR-ARN-EWR-BTV if that's the case.
Last edited by photodave; Dec 30, 2008 at 2:19 pm