- if stock_change.stock_article.new_record?
  = simple_fields_for "delivery[new_stock_changes_new_stock_article][]", stock_change do |f|
    = render :partial => 'stock_change_fields', :locals => {:f => f}
- else
  = simple_fields_for "delivery[new_stock_changes][]", stock_change do |f|
    = render :partial => 'stock_change_fields', :locals => {:f => f}