If you have a Drupal 7 view with more than one attachment display, it is not super-obvious how you can reorder the displays. When you create a new attachment display, you can choose the display to attach the attachment display to as well as the position ("before", "after", or "both").
But what if you need to attach two attachment displays "before" another display - how can you control the order of the two attachment displays.
it's actually quite easy once you know how - in the view's "edit view name/description", there is a "reorder displays" option. Click it and behold!
For me, even though I was reordering views in that way, it doesn't work until I have changed the system display name. I had set two attachments before a page, but these two attachments finally have been ordered by their system name (alphabetical order).
Maybe this can help.