1. Multiple accounts are allowed.
(1.5.) It's even allowed to play them at the same time (if I remember correctly - don't quote me on that)
2. Multiboxing is
NOT allowed.
3. Sharing accounts is
NOT allowed. (I don't know if this applies to your case as your friends aren't playing anymore.)
If you are unsure -> just write a friendly mail to
. They will most probably help you out
P.S.: You might want to use the alt accs for daily crafting too. Extra profit there.