  The arcs of Neptune - Fraternit\'e, Egalit\'e, Libert\'e, and Courage - are
four incomplete rings immersed in the Adams ring. A recent confinement model
for the arcs proposes that the structures are azimuthally confined by four
co-orbital moonlets. In this work, we intend to approach some points related to
the dynamics of co-orbital moonlets and suggest a model for their formation. We
study the equilibrium configurations for 1+N co-orbital satellites under the
42:43 Lindblad resonance with Galatea. We obtained three distinct
configurations with 1+3 and 1+4 moonlets able to confine and reproduce the
location of the arcs. The moonlets' formation is analysed by the disruption of
an ancient body at a Lagrangian point of a moon. The disruption fragments
spread out in horseshoe orbits and collide to form moonlets, which reach an
equilibrium configuration due to a non-conservative effect. In such a scenario,
the arcs likely formed through a mixture of different processes, with impacts
between disruption outcomes and meteoroid impacts with the moonlets being
possibilities.
