This document specifies methods and procedures to form groups for a spatial wireless power-transfer system. The group of spatial wireless power-transfer systems that include multiple power sources provides power transfer to receiving devices based on magnetic resonance technology. In order to achieve efficient power transfer to multiple receiving devices@ this document also specifies methods and procedures to set@ share@ and control the conditions of power transfer between multiple power sources and receiving devices. NOTE Expected power-receiving devices are audio@ video and multimedia equipment.