Would something like this work?

account_service.rb

module UCP
  class AccountService
    attr_writer :cs_acct_service, :bsil_acct_service

    def initialize(cs_acct_service, bsil_acct_service)
      @cs_acct_service = cs_acct_service
      @bsil_acct_service = bsil_acct_service
    end

    # This is where 'workflows' can live.  If they aren't sync,
    # then we'll invoke them w/ sidekiq or something instead.
    def create(composite_account)
      cs_acct = composite_account.to_cloudstack
      bsil_acct = composite_account.to_bsil

      begin
        @cs_acct_service.create cs_acct
      rescue
        # recovery?
      end

      bsil_acct.some_cs_thing = cs_acct.id

      begin
        @bsil_acct_service.create bsil_acct
      rescue
        # recovery?
      end

      true
    end

    # No abstraction?  Nope. If you passed in a populated model,
    # have you simplified things or made them harder?
    def find(cs_id, bsil_id)
      cs_acct = @cs_acct_service.find cs_id
      bsil_acct = @bsil_acct_service.find bsil_id

      UCP::Account.new cs_acct, bsil_acct
    end

    def update(composite_account)
      # same as create I think
    end
  end
end