In this paper, we present a method to investigate and control the dynamics of the nearby host nuclear spins (the ‘frozen core’) about a rare-earth ion doped in a crystal. Optically detected, double quantum magnetic resonance measurements were conducted on Eu3+:Y2SiO5. The distinct magnetic resonant frequencies of nearby Y3+ spins were measured along with the lifetime and coherence time of an individual Y3+ spin. We demonstrate an entangling gate between the Eu3+ spins and a Y3+ spin associated with a particular position. Further, we propose a method to initialize the Y3+ spin states, enabling the Y3+ spins to be used as a quantum resource for quantum information applications.