  Single-layer $\it{h}$-BN is known to have edges with unique magnetism,
however, in the commonly fabricated multilayer
$\text{AA}^{\prime}$-$\it{h}$-BN, edge relaxations occur that create interlayer
bonds and eliminate the unpaired electrons at the edge. Recently, a robust
method of growing the unconventional Bernal-stacked $\it{h}$-BN
(AB-$\it{h}$-BN) has been reported. Here, we use theoretical approaches to
investigate the nitrogen-terminated zigzag edges in AB-$\it{h}$-BN that can be
formed in a controlled fashion using a high-energy electron beam. We find that
these "open" edges remain intact in bilayer and multilayer AB-$\it{h}$-BN,
enabling researchers potentially to investigate these edge states
experimentally. We also investigate the thermodynamics of the spin
configurations at the edge by constructing a lattice model that is based on
parameters extracted from a set of first-principles calculations. We find that
the edge spins in neighboring layers interact very weakly, resulting in a
sequence of independent spin chains in multilayer samples. By solving this
model using Monte Carlo simulations, we can determine nm-scale correlation
lengths at liquid-N$_{2}$ temperatures and lower. At low temperatures, these
edges may be utilized in magnetoresistance and spintronics applications.
