A network function and a method for associating a UE of a UE group to a PDU session with in a CN. The NF establishes a shared PDU session for the UE group before all of the UEs in the UE group register with the CN and binds a UE that has not yet registered with the CN to the shared PDU session when the UE registers with the CN, provided the UE will share at least one of a UL UP connection and a DL UP connection associated with the shared PDU session. The NF may be an SMF.