The embodiments herein relate to a method performed by a Control Plane (CP) function for handling a credit pool comprising granted service units to be used by multiple services. The multiple services are grouped in at least one first Rating Group (RG). The CP function creates an individual Usage Reporting Rule (URR) for each of the at least one first RG. Each individual URR comprises a first credit pool threshold. The CP function provides the individual URRs to a User Plane (UP) function. The CP function creates a Usage Reporting Rule for the Credit Pool (URR CRPL). The URR CRPL comprises instructions to the UP function to aggregate service unit usage for all individual URRs for all first RGs. The URR CRPL further comprises the first credit pool threshold. The CP function provides the URR CRPL to the UP function.