  We present neutron diffraction data for the cubic-heavy-fermion YbBiPt that
show broad magnetic diffraction peaks due to the fragile short-range
antiferromagnetic (AFM) order persist under an applied magnetic-field
$\mathbf{H}$. Our results for $\mathbf{H}\perp[\bar{1}~1~0]$ and a temperature
of $T=0.14(1)$ K show that the $(\frac{1}{2},\frac{1}{2},\frac{3}{2})$ magnetic
diffraction peak can be described by the same two-peak lineshape found for
$\mu_{0}H=0$ T below the N\'{e}el temperature of $T_{\text{N}}=0.4$ K. Both
components of the peak exist for $\mu_{0}H\lesssim1.4 T$, which is well past
the AFM phase boundary determined from our new resistivity data. Using neutron
diffraction data taken at $T=0.13(2)$ K for $\mathbf{H}\parallel[0~0~1]$ or
$[1~1~0]$, we show that domains of short-range AFM order change size throughout
the previously determined AFM and non-Fermi liquid regions of the phase
diagram, and that the appearance of a magnetic diffraction peak at
$(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ at $\mu_{0}H\approx0.4$ T signals
canting of the ordered magnetic moment away from $[1~1~1]$. The continued
broadness of the magnetic diffraction peaks under a magnetic field and their
persistence across the AFM phase boundary established by detailed transport and
thermodynamic experiments present an interesting quandary concerning the nature
of YbBiPt's electronic ground state.
