"She is with us for the time being," a source at the rehab center told Radar. "We expect her to stay for the full 90 days, however she could bounce because there is no court order ensuring that she has to stay."
Radar also reports that when Lindsay faces the judge at her October 22 probation violation hearing, she will plead to remain in rehab and have jail time deferred or avoided.
"Lindsay is still being assessed by her treatment team but the team is saying that she should spend at least 45 days getting in-patient treatment. It's going to take her body at least 30 days to get the substances out of her system," a source told the website. "Her body needs to do a lot of healing, and the doctors want to treat her after the remnants of the drug use have left her body. The real work begins after that has occurred, and that is when progress begins to happen."
Lindsay's hearing falls only three and a half weeks into her treatment.
Meanwhile, Lindsay's brother Michael Jr., 22, has spoken to People about her problems.
"People she was surrounded by - enablers, leeches, whatever you'd like to call it - made things very difficult," he said.
But Michael believes Lindsay has learned from her troubles and is committed to recovery.
"She has made conscious efforts to improve her lifestyle behaviors and to treat this process with great care," he told People. "In order to continue her healing process, she's willing to take whatever steps necessary."