Friday February 01, 2013 11:00 AM EST

Ashlee Simpson Praises Sister Jessica as a 'Great Pregnant Lady' and Mom

by Andrea Billups and Gabrielle Olya

Ashlee Simpson has nothing but praise for her sister Jessica as a great mom – and as a mom-to-be.

"Jess is awesome," Simpson told PEOPLE in the way of a pregnancy update on her sister, who's expecting her second child. "I think we both equally look up to each other ... [She's] my big sister and I'm proud of her."

"And she's a great mom – and a great pregnant lady," Ashlee continued.

The younger Simpson, 28, joined her gal pals for a night out Thursday at Los Angeles's Pink Taco for a Svedka vodka-sponsored "Throwback Thursday" party, featuring performances by acts including All-4-One and Debbie Gibson.

There she rocked out to '90s tunes with her cousin, her best friend and her publicist, wearing an Izmaylova dress with a Lizzie Fortunato necklace, her blonde hair pulled up high in a sleek top-knot. She took to the floor to slow dance with a friend and then passionately belted out retro tunes.



Simpson also told PEOPLE her son Bronx has bonded nicely with Aunt Jessica, 32, and her daughter Maxwell, 8 months.

"Bronx loves her, Bronx loves Maxwell, we're all there," she said of their growing extended family as a new baby is on the way and Jessica works to create a new TV show based on her life.

"She's got all our support, naturally, but she's a strong woman," said Ashlee. "[She's a] woman to look up to and a big sister I'm proud of."

Bronx, she added, is also happy about welcoming another baby into their family.

"He's excited for the new one!" Simpson said.