Originally Posted by BOSTransplant

Emphasis mine. Are you sure that this was done automatically? I've never heard of a ticketing change being made automatically because of an oversell. To my knowledge, the only automatic rebooking that occurs on DL is the rebooking that VIPER does in the case of delays. Are you sure a DL agent (either at the gate or at check-in) didn't ask your in-laws if they would be willing to take the nonstop? If that's the case, and your in-laws agreed to it without asking for any kind of compensation or refund of fees, then I don't really think you have a leg to stand on to ask for any kind of reimbursement or compensation.