"He's wonderful," Ashlee Simpson-Wentz told PEOPLE of Jessica's new fiancé at the launch party of Google's Boutiques.com in New York on Wednesday. "They're so easygoing together. They really bring out the best in each other. It's beautiful."
Ashlee, 26, says she and the family are "beyond excited" about the upcoming nuptials, but adds that the wedding planning hasn't really started yet. "Right now we're just really enjoying the engagement and their happiness," she says.
Ashlee's words echo those of Jessica's dad, Joe Simpson – who wished Jessica and Eric a "lifetime of joy and happiness" – and Pete Wentz, who said he was thrilled to see his sister-in-law so happy.
Ashlee, meanwhile, has has another celebration on her mind: son Bronx Mowgli's second birthday this Saturday. "We're going to have a get together at my mom's, so it'll be fun," she says.
Luckily, it seems Bronx isn't suffering from the terrible twos. "He's so sweet, he's very sweet natured," Simpson-Wentz says. "He's really into Thomas the Train, and now he's watching movies sometimes. and I'm like, 'Whoa!' It's so crazy."