  We prove a weak-strong uniqueness principle for varifold-BV solutions to
planar multiphase mean curvature flow beyond a circular topology change:
Assuming that there exists a classical solution with an interface that becomes
increasingly circular and shrinks to a point, any varifold-BV solution with the
same initial interface must coincide with it, and any varifold-BV solution with
similar initial data must undergo the same type of topology change. Our result
illustrates the robustness of the relative energy method for establishing
weak-strong uniqueness principles for interface evolution equations, showing
that it may also be applied beyond certain topological changes.
