To follow up on your baggage comments:

The airline carrying the passenger to the final destination is responsible for the luggage...if Delta still has the bags, so be it, Northwest must take the claim if she arrives in SBN on NW. This is always the case... with few exceptions (when airlines like Southwest are involved and there is no baggage agreement.)

Bottom line: NW should take the claim at SBN should the bags not arrive with her. Might check at the Delta office first though to see if perhaps they carried them in without her. I too, would write Delta. Once Delta issued a boarding pass for your granddaughter she was their passenger...sending her back to NW was WRONG. It was an easy out for Delta when they saw a problem with their flights in CVG.
The mother should have been allowed a gate pass, in my opinion...we do have "some" discretion on issuing them and even though you didn't want to have the UM service from the carrier, I think it's reasonable that your granddaughter be accompanied to the gate.


Good luck!