the same thing happened to my friend NINJABOSS935 (new username FrankleBomber) luckly I was the coop leader so I was able to reivite him. it says that Both users are in my coop though.
Actually, you can. XD You can't 'sleep' like SinglePlayer, but your /homes get set there if you stay in the bed for over 3 seconds.
Remember you need to: 1) Be online NET 2) /msg a Red or Dark Red Mod 3) If they locate your island, make a bed there and sleep there 4) Note down the coords of ur island, so you can be TP'ed there easily if something happened to ur bed 5) Get the mods to break the signs on your chest and then replace them ASAP with signs of ur new name 6) You can do /homes in the future to get back to your island while the server gets upgraded to 1.8