I am so sorry, I would be sick as well.
Last week, we had a package sent to us with delivery confirmation and when i checked the tracking number, it said it was delivered, but we hadnt received itm we checked all the doors and nothing...I called the PO to check, and he said it was a sub mail carrier working that day, he'll ask him if her remembers that package, of course i didnt hold my breath for that. The next day, one od our neighbors brough it over, and said it was in their box :!: go figure!
Maybe it was accidentally delivered to a neighbor? Can your cousin check with them? Does she kniw any of them well enough to ask around?