The bloodlines of Anárion and Isildur were reunited by the marriage of Anárion's descendant, Fíriel of Gondor, with Isildur's descendant, Arvedui of Arthedain.
This palantír was used by the Kings of Gondor, but when Minas Ithil fell to the Ringwraiths, Eärnil II stopped using it; not only did Sauron now have access to the network, but the palantír of Anárion had the strongest link of all seven to the Ithil-stone.