I see one or two of those, they look valid to me if you can find a TA who will issue the ticket.
Example fare construction is
Code:
MSP UA X/CHI 212.09QAA0AKDN DL X/NYC DL BTV 246.51KAVTA0MQ USD 458.60 END ZP MSP ORD LGA XT 34.40US 13.50ZP 5.60AY 9.00XF MSP4.50 ORD4.50
Checking the Category 10 (fare combinations) for both fares, they allow end-on-end for the other fare. And no restriction to prevent plating on a particular carrier's ticket paper.
However, whether in the event of disruption you got your problem resolved quickly, I don't know.