  We here present an extension of the CKKW-L multi-jet merging technique to
so-called sector showers as implemented in the Vincia antenna shower. The
bijective nature of sector showers allows for efficient multi-jet merging at
high multiplicities, as any given configuration possesses only a single
"history", while retaining the accuracy of the CKKW-L technique. Our method
reduces the factorial scaling of the number of parton shower histories to a
constant of a single history per colour-ordered final state. We show that the
complexity of constructing shower histories is reduced to an effective linear
scaling with the number of final-state particles. Moreover, we demonstrate that
the overall event generation time and the memory footprint of our
implementation remain approximately constant when including additional jets. We
compare both to the conventional CKKW-L implementation in Pythia and gain a
first estimate of renormalisation scale uncertainties at high merged
multiplicities. As a proof of concept, we show parton-level predictions for
vector boson production in proton-proton collisions with up to nine hard jets
using the new implementation. Despite its much simpler nature, we dub the new
technique MESS, in analogy to the conventional MEPS nomenclature.
