  We continue the study of null-vector equations in relation with partition
functions of (systems of) Schramm-Loewner Evolutions (SLEs) by considering the
question of fusion. Starting from $n$ commuting SLEs seeded at distinct points,
the partition function satisfies $n$ null-vector equations (at level 2). We
show how to obtain higher level null-vector equations by coalescing the seeds
one by one. As an example, we extend Schramm's formula (for the position of a
marked bulk point relatively to a chordal SLE trace) to an arbitrary number of
SLE strands.
  The argument combines input from representation theory - the study of Verma
modules for the Virasoro algebra - with regularity estimates, themselves based
on hypoellipticity and stochastic flow arguments.
