If Christmas presents get lost in transit, should the sender feel obligated to purchase new presents?

USPS lost presents I sent to my two nieces. I didn't insure them, but I did replace them.

Now a relative of mine dropped off presents for my children at a location that ships Fed Ex. They were in the Fed Ex system with a weight, tracking number, arrival date, but only one out of four bars. The location doesn't seem to be able to find them and Fed Ex says its computers show that it didn't receive them. Fed Ex says that the data in the system is what goes in when the third party arranges to ship packages. It doesn't seem like my relative will be able to locate them and furthermore it doesn't seem like any company is going to take responsibility for the probable theft. To make matters even stickier, my relative works for the company that lost her package. The package contained items she bought at her workplace.

What is the right thing to do in this situation?