  We consider a spin-$j$ particle coupled to a structured bath of bosonic modes
that decay into thermal baths. We obtain an analytic expression for the reduced
spin state and use it to investigate non-Markovian spin dynamics. In the
heavily overdamped regime, spin coherences are preserved due to a quantum Zeno
affect. We extend the solution to two spins and include coupling between the
modes, which can be leveraged for preservation of the symmetric spin subspace.
For many spins, we find that inter-mode coupling gives rise to a privileged
symmetric mode gapped from the other modes. This provides a handle to
selectively address that privileged mode for quantum control of the collective
spin. Finally, we show that our solution applies to defects in solid-state
systems, such as NV$^{-}$ centres in diamond.
