Well, for now I'd have to say that sucks. Big time.
Dreadfully sorry to hear about it too. there's no question that one half of a matched pair being lost or busted IMO is a total loss... and I'd pursue it that way too, wether it would prove out well or not for me... as pairs of things are usually matched, or at least they're in the same build era.
I had an issue with a pair of speakers once with Fed Ex. They picked them up in MI at about 3pm one day and miraculosly delivered them by ground, some 1800 miles in 2.5 hrs.!!
For three days they had no idea where they were but gave me the delivery address. Not mine either. One about eight miles from where they were picked up!
Several days later one supervisor found it all out... they had been delivered and scanned into a local Fed ex station... but never scanned again when they were shipped out from there to me.
I understood why when they arrived... the cardboard covering the plywood box was nearly all gone from one unit, and the other's was torn almost all off. hurray for plywood boxes and closed cell foam liners!
A couple other wierd shipping issues forced me to ensure that when ordering amps or speakers in 'pairs' (if large and/or expensive), to palletize 'em. in fact I flew in my Dodds from WA. overnight hoping to circumvent any loss. Palletized my DD15 when it was shipped within the state to me as well... but it still got a fork lift hole in the outer box! thankfully not on the sub itself though.
There is a place which will ensure Fed Ex deliveries against loss or theft apart from the declared value you submit to Fed Ex. there are some criteria too that must be met, such as covering the box so no name or mention of it's contents can be determined, and I think therre's a 30 14 or day wait to recover as well.... and it's only for Fed Ex shippments too.
Duct tape 'em together and - or band them onto a pallett is now my ongoing preff and whenever it's a pricey item, I'll use Pilot Air... still there's just no gimme or lock, on the outcome of shipping stuff.
I sure hope all turns out well, and it probably will. Keep a good thought.