I contacted DL about the $35 ticketing fee and am happy to report that DL responded a week later by making a one time exception and refunded the fee. I do not have status on DL and feel that DL should not charge a fee to any pax for a transaction that cannot be completed online and that requires agent intervention. Furthermore, their reservation and ticketing staff need to be trained better. It shouldn't take 40 minutes on the phone and another hour at the airport to process this type of transaction. Would be nice to speak directly to "global" since they seem like the only department familiar with lap child tickets.
That said, I hope that DL adds to their list of dot.bomb issues to fix, the ability to purchase an infant lap child ticket online when making adult reservations. B6 and UA have this ability.