She told BBC Radio Sussex: “They want to be closer to their family and friends and continue with their education.
“We are continuing to adapt to increased demand on services.
“This is enhancing our offer for young people with significant mental health difficulties.”
Evie, who was admitted into inpatients for six months, is helping with the Sussex scheme.
She said: “Having a perspective from someone my age who has been through similar things to me would have really benefited me.
“It is about how we can make the system better.”
Dulcie, another former service user, said: “People who are now in a better place can communicate with the professionals to improve outcomes for everybody.
“I think it’s good to use people who have used the services themselves as they know how it is from a first-hand perspective.”