A method for a target mobility management entity and a target mobility management entity for executing the method in a core network to communicate network function (NF) utilization information with a source mobility management entity during a change of mobility management entity are disclosed. The method comprises: receiving at least one old NF identifier (ID) from the source mobility management entity that corresponds to an old NF entity serving a user equipment (UE); determining to either use the at least one old NF ID or to use at least one new NF ID that corresponds to a new NF entity of a same NF type as the old NF entity; and communicating, to the source mobility management entity, information that indicates to the source mobility management entity whether the target mobility management entity uses the at least one old NF ID or uses the at least one new NF ID.