«The Fledglings» by E. DeLaurentis

The ethereal Sakrosians existed for millennia, relying on their collective energy to conjure a magnificent city. Not content to remain unchanged while creatures of the Gaia developed, the Secrecy Magistrate experimented with creating a new species. But the Fledglings didn’t embody Sakrosian ideals as intended. The Prophetess, Lita, convinced the Council that Fledglings had the potential to evolve, if a Directive was established to ensure their survival.
El, the Seer, conveys to the Council her visions of Fledglings as they disperse across the Gaia. What she sees makes her question why Sakrosians are discarding their form to become inferior creatures.
When the Council decides Fledglings should inhabit Terrenor, a northern land reached only by crossing treacherous terrain and a Great Divide, El wavers between thwarting the travelers—hoping Councilors will change the Directive—or helping the Fledglings when she realizes that some possess Sakrosian skills.
Until El understands why Sakrosians made the decision, which threatens their existence, she can’t fully accept the Directive. What El discovers is the secret the Council is unwilling to acknowledge.
 
The story continues in Sakrosians Series Book 2, The Fledglings ~ A Winding Path, and concludes in Book 3, The Fledglings ~ A Beacon