Single-Molecular Magnets (SMMs) provide access to the mesoscopic world. They possess slow magnetization relaxation due to an energy barrier induced by axial magnetic anisotropy, which makes them potential candidates for quantum computing, high-density storage and magnetic refrigeration. It is essential to improve blocking temperatures and control of quantum effects in SMMs for such applications. Zadrozny suggested that the magnetization relaxation in SMMs is governed by four processes (direct, quantum tunnelling (QT), Raman and Orbach), but they have never been thoroughly studied within a single material, or perhaps more importantly, how they differ has not been studied in a series of closely related materials. We propose to investigate the magnetisation fluctuations in two members of the CP*-RE-COT series at high temperatures to obtain a whole story of fluctuations in all materials.