Technically, this is not illegal. The two parties are members of the same family, and they share the same bill. Their ISP has no issues with this. They live in a remote area, and A's connection is a Trango long range (about 6 miles) wireless, with maximum throughput of 10 mbit/s, but usually capped at 2 mbit/s. Also, they are located in Canada, where things are slightly different.