<p><span></span>Now that she's 18 years old, <a href="http://dynamic.bauerpublishing.com/mt-search.fcgi?blog_id=2&tag=lindsay lohan&limit=20&IncludeBlogs=2"><strong>Lindsay Lohan</strong></a>'s model sister, Ali, would like to be called by her full name, <a href="http://dynamic.bauerpublishing.com/mt-search.fcgi?blog_id=2&tag=aliana lohan&limit=20&IncludeBlogs=2"><strong>Aliana Lohan</strong></a>.</p>
Multiple sources confirm to Life & Style she prefers the name Aliana, because it sounds more mature.
And with her passage into adulthood, the Lohan family (sans father Michael) feted Aliana with a birthday celebration at Beaumarchais restaurant in NYC on Dec. 21.
Lindsay, along with a group of her friends, mom, Dina, and younger brothers Cody and Michael Jr. -- who was celebrating his 24th birthday -- ordered from a prix fixe menu that included tuna tartare and truffle gnocchi.
"It's clear Lindsay and Michael Jr. are very close. They were talking a lot and Michael had his arm around her at one point. She seemed to be confiding in him," an eyewitness tells Life & Style. She also went outside to smoke cigarettes with her mom at one point.
But a celebration wouldn't be much without champagne!
Later on in the evening, the Playboy cover girl requested just that.
"Lindsay ordered a bunch of glasses of champagne for the table and switched to drinking that," the eyewitness tells Life & Style.
During the big bash, Lindsay and Aliana snapped photos together on Lindsay's camera before Lindsay got up to ask the restaurant staff to prepare a cake and champagne sparklers for the table. "The staff brought out cake and two brownie sundaes while everyone sang," the eyewitness tells Life & Style. "Lindsay toasted with champagne."
Although Aliana is super svelte, she doesn't seem to be watching what she eats. Adds the eyewitness, "She had a lot of bread, a big salad and a bunch of her brownie sundae."
Photo Credit: Startraks