Jessica Simpson threw her son a "Moana"-themed birthday party this week. The 36-year-old singer and designer celebrated son Ace's fourth birthday with husband Eric Johnson, 5-year-old daughter Maxwell and other family and friends. Simpson enlisted the help of friend Stephanie Terblanche to create the Isle of Te Fete, the fictional Polynesian island in Moana, for the bash. Guests enjoyed airbrush tattoos, a bounce house and personalized party favors as they mingled with actors dressed as Moana and Maui. The "With You" singer shared several photos from the fete on Instagram. One picture shows Ace holding a stuffed version of Moana's rooster Heihei as he poses with Simpson, Johnson, Maxwell, Moana and Maui. "#ACEKNUTE #4 [party by] @baylormcg \/\/ [photos by] @kristingram," Simpson captioned the slideshow. Simpson and Johnson married in 2014, but celebrated their seventh anniversary as a couple in May. The singer denied on "The Ellen DeGeneres Show" the same month that she and Johnson plan to have more children. "I'm not pregnant on your show," she told host Ellen DeGeneres. "We got an IUD. Nothing's going to get in that uterus." "I have two beautiful children and I'm not having a third. They're too cute. You really can't top that," the star explained. Reality stars Kourtney Kardashian and Kim Kardashian threw their respective daughters, Penelope Disick and North West, a Moana-themed joint birthday party in June. The Disney movie opened in theaters in November.