Mai poured over that book and found one chakra healing technique that would work on draconians that also involved her bloodline... She'd have to show Rowen the book. There were only four known copies of the book. One belonged to her father, another was in an archive, the third was floating around private collections and she had the fourth. The healing technique in question was dangerous for Mai to use. It could result in severe injury and had to be performed with complete cooperation on the draconian's part. It used mostly the draconian's own chakra and once the healing was done Mai's own chakra would have to be withdrawn for the sake of stability.
Mai found Rowen curled up in a hollow of a tree and showed her the book explaining how rare it was and that it was a gift from Mai's father. AND the only source of medical information Mai had on Rowen so destroying Mai's copy of the book could prove fatal one day. She also showed Rowen that she had been censoring pages that could be used to inflict harm on a draconian. Mai made the offer to fix the wing. She had a chakra tournaquit on her arm for her own protection.