No drama for this baby mama! Expectant Ashlee Simpson didn't leave her sister Jessica's side at the grand opening of Palms Place in Las Vegas -- and the aunt-to-be had nothing but praise for the mothering skills of her little sis.

"She'll be amazing, absolutely amazing," Jessica told
People magazine
at the grand opening of Palms Place in Las Vegas.

Jessica, who is giving country music a whirl, also dished that the love between Ash and Fall Out Boy hubby Pete Wentz is inspirational for her love-heavy lyrics, saying, "They're just the cutest couple in the world -- they're adorable," adding, "Just being around them inspires love and everything I sing about."

Pete Wentz deejayed the event -- and at the end of his stint, he gave Ashlee a shout-out by thanking his "baby mama."