The European Tour regulars, along with Australian youngster Cameron Smith, secured the privilege courtesy of their high finishes in the US Open at Chambers Bay.
Irishman Lowry finished in a tie for ninth, five places behind South African Grace, who went into the final day in a tie for the lead but finished the tournament fourth after closing with a one-over 71.
They have all earned more non-member FedEx Cup points than the total of the player who finished 150th on the list in 2014.
England’s Danny Willett and up and coming United States player Patrick Rodgers also secured invites in similar fashion earlier in the season.
They are now eligible for unlimited sponsor exemptions for the remainder of the Tour season as they attempt to earn 2015-16 cards through the non-member money list or non-member FedExCup points list.
Special temporary members are not eligible for the FedExCup play-offs, but they can become regular PGA Tour members by winning an official event during the season and would then have their FedExCup points counted and be eligible for post-season play.