An excerpt from "Boy Singers' Vocal Change: A Positive Approach"
http://www.21stcenturychorister.com/chorister/articles/boysi ngers.html
Mr. Leck believes however, that a boy should keep singing through the change; that his high voice is actually the foundation for his new, lower voice. A boy who stops singing altogether during the change may lose the ability to manage his voice. Leck advocates a boy using his high voice while his voice is changing, and continuing to do descending exercises down across the register break. He encourages boys to keep singing through the transition, because in addition to allowing the voice to continue developing while the new voice is settling in, it may even have the positive result of a singing voice without a break. In his mind, there are few reasons not to sing while the voice is changing.
Henry Leck does point out though, that continuing to sing in a high voice when the voice is changing can create unique challenges and frustrations, and so gives other tips on how to manage during this transition period. A boy may be psychologically uncomfortable regarding the unpredictability of his singing at this time. Mr. Leck suggests that it may put him at ease to vocalize with an older male singing instructor. It is very important to be open about the situation, keeping excellent communication between singer and director. This allows for an environment where both singer and director are aware that each other knows what is going on, and a unique plan for the particular boy can be designed. Tiring quickly when only the high voice is used for long periods is a reality, so continuing to monitor a boy's comfortable singing range and allowing him to rest when needed is most important. It is even desirable to allow him not to sing certain notes or parts of a song. This flexible approach, unheard of only a short time ago, is truly welcome to those who want to continue singing, even as their voice changes.