Kim and Kyle Richards both sent birthday wishes to their older half-sister, Kathy Hilton.

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Although family tensions between the women have been high in recent years, Kim shared a message and photo on Instagram for Hilton on Sunday, and Kyle shared a photo collage.

"Happy Birthday to My Beautiful Beautiful Sister Kathy ... I love you so much," Kim wrote. "You are an amazing Sister, Mother, Wife & Friend thank you for always be there .... I am so grateful & proud to have you as MY SISTER!"

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A photo posted by Kim Richards (@kimrichards11) on Mar 13, 2016 at 3:39pm PDT

During the currently airing sixth season of The Real Housewives of Beverly Hills, Kyle's feud with Kathy was exposed during an early episode, when it was revealed that Kathy had disinvited her from the wedding of Nicky Hilton, which took place in July of last year in London. And although Kyle eventually did attend the ceremony, her husband, Mauricio Umansky, and their daughters, Sophia and Alexia, did not.

"Happy birthday to my sister @kathyhilton! May all your wishes come true. Love you," Kyle said.

A photo posted by Kyle Richards Umansky (@kylerichards18) on Mar 13, 2016 at 8:39pm PDT

For more of Kim and Kyle Richards, tune into The Real Housewives of Beverly Hills season six, airing on Tuesday nights at 9 p.m. on Bravo, and check out a sneak peek at the upcoming episode below.