The combined Pacific Island team has been told by the IRB that any one who plays in their games against the Tri-nations sides in July will not end the player's chances of playing for another country.
Pacific Islanders Rugby Alliance chief executive Charlie Charters said that the IRB ruling potentially expands the pool of players they are able to select.
The world body had ruled that playing for the Islanders did not "capture" a player's eligibility, making them unable to be selected for other teams, he said.
Under current IRB regulations, a player can only play for one country in his rugby career once his eligibility has been "captured" by selection for a national 15, national A side or national sevens team.
Charters said the ruling stated: "If a player who is eligible to play for both Fiji and New Zealand but has not actually represented either of these unions plays for the Islanders team, he will not be captured by either of these unions."
"This is an important clarification that we have been given by the IRB and allows us to communicate to our potential player pool what playing for the Islanders will mean in all respects," Charters said.
The ruling potentially opens the door for players like Waikato Chiefs' Deacon Manu and Wellington Hurricanes' Sione Lauaki, who have yet to play Test rugby, to join the Pacific Islanders without jeopardising their New Zealand contracts.
Charters described the ruling as an "ace up the sleeve" for selectors who will pick a 30-man squad for the upcoming Tests after the Pacific Tri-Nations Series ends on June 12.
"We want the Islanders to make the national unions of Fiji, Samoa and Tonga stronger in all respects and the best way to do that is to encourage our elite players to play for those countries over all other options," said Charters.
He said he expected the vast majority of the Islanders squad to be made up of players who had already played for one of the three unions.