Попробуйте что-то вроде:
class User < ActiveRecord::Base
...
has_many :published_reports, :class_name => "Report", :conditions => "reports.published = 1"
has_many :unpublished_reports, :class_name => "Report", :conditions => "reports.published = 0"
...
end
class UsersController < ApplicationController
active_scaffold :users do |config|
...
config.actions = [:nested, :list, :show, :field_search]
config.nested.add_link("Published", :published_reports)
config.nested.add_link("Unpublished", :unpublished_reports)
...
end
end