Originally Posted by
MSPeconomist
Since it's a family of three, be aware that DL can charge you the UM fee if a kid under 15 is not in the same cabin as an adult, so be careful who you try to upgrade with you. OTOH, I don't think a PM has much chance of getting an upgrade to/from HNL on most flights/dates.
Travelled many times with kids younger than 15 in different cabins on the same aircraft. Never once been charged an UM fee.