A Sidelink AS group management function is disclosed for a UE to discover group members and organize them into AS layer sub-groups based on the AS layer group context information. A centralized Sidelink AS group management is disclosed that the Sidelink AS Group Manager discovers group members and organizes them into AS layer sub-groups for a UE. A Subgroup formation and configuration procedure is disclosed that SL AS Group Manager organizes the ULG into AS layer sub-groups, configures UE-to-UE relays for each UE in the ULG and sends the AS group management information to the UE. A distributed Sidelink AS group management method is disclosed that each UE discovers its group members and organizes the ULG into AS layer sub-groups. New Layer 2 structures and procedures are disclosed to enhance bearer management for Sidelink groupcast communications.