This work studies the interaction between Radio Frequency (RF) waves used for Ion Cyclotron Resonance Heating (ICRH) and the fast D and T Neutral Beam Injected (NBI) ions in DT plasma. The focus is on the effect of this interaction, also referred to as synergistic effects, on the fusion performance in the recent JET DTE2 campaign. Experimental data from relevant diagnostics were analyzed and conclusions were drawn and supported by modelling of the synergistic effects. TRANSP runs with and without RF kick operator predicted moderate increase, about 13%, in DT rates for the case of RF wave – fast D NBI ions interactions at n=2 harmonic of ion cyclotron resonance and negligible impact by synergistic interaction between fast T NBI ions and RF waves. JETTO modelling gives 29% enhancement of fusion rates due to RF waves – fast D NBI ions interaction and 18% enhancement for fast T NBI ions. Analysis of experimental neutron rates compared to TRANSP predictions without synergistic effects and Magnetic Proton Recoil (MPRu) neutron spectrometer indicate approximately 25% enhancement of fusion rates due to RF interaction with fast D ions and approximately 5-8% when RF wave – fast T NBI ions interaction is taking place. Contribution of various heating and fast ion sources have been assessed and discussed.