You misrepresent the rules. The rules do not state that trading between nations that share a network is prohibited. They say that a trade created on a network cannot be completed by a nation on that network. This is a description of the hard-coded limitation, not a description of a prohibited activity. Nations that occasionally share an IP can trade with one another, so long as the offers are made and accepted from different IPs and it is clear to Sheepy that the nation's are not being managed for the sole benefit of one of them.