I recently attended a polyamorous wedding where one pair of individuals in the polycule were formalizing their individual bond/commitment to each other (but both still remaining in the larger structure of the 5-6 person polyromantic/polyamorous constellation.) It was cute! All the other members of the group walked the bride and groom down the aisle and gave cute best-man-style speeches instead of a religious ceremony.
I enjoyed the event and they all seemed really happy.