  We propose a new model for multicategories with symmetries with respect to
Zhang's group operads. The fully faithful embedding of the category of group
operads into that of crossed interval groups is made use of, and it is shown
that every multicategory gives rise to a fibration, in a sense, over a quotient
of the total category of group operads. The symmetric structures can be
presented as structures of internal presheaves over a category internal to the
category of small categories, in other words a double category.
