In 2023, the technical requirements for frequency containment reserve - disturbance (FCR-D) in the Nordic synchronous area were revised, introducing stricter demands on dynamic response and new stability criteria. Hydropower plants (HPPs) constitute the largest share of FCR-D provision in the Nordic region. However, HPPs exhibit inherent dynamic delays, which may prevent some units from complying with the revised requirements. A hybrid solution with a fast-acting energy storage system (ESS) is therefore proposed to assist the HPP, enabling the hybrid plant to fulfil the requirements for FCR-D. This paper models a Kaplan HPP in Sweden which fails to meet the revised FCR requirements on its own. A dynamic parallel power sharing strategy between the HPP and ESS for primary frequency control within a hybrid power plant is proposed. Both battery energy storage system and supercapacitor energy storage system are considered for the hybrid plant, and the most cost-effective configuration is explored.