The family member should have a paper copy of the entire e-ticket receipt with him and should raise the issue should the check-in agent at SHD attempt to charge the fee. The family member should also have his CC ready in case the fee is charged. All the rest comes after the fact and isn't worth arguing about at the check in counter.

The bottom line is that even if UA has issued an incorrect receipt, that does not entitle the passenger to enforce the lower limit. Rather, it may result in DOT fining UA (unlikely) but that does not really help the family member.

Just a guess, but I am willing to bet that the SHD agent will "honor" the e-ticket receipt allowance.