I liked everything RMA wrote in his reply post, except making a big deal about the "precious dress". I understand your bags said crew (all your entourage's bags were labeled special?). I never have nor will I lie about crew status for myself. My husband is entitled to that status, not I.
If the dress was that precious, it should have been in your possession, not checked. I know that sounds callous, but I stand by this: if you can lose any item, it's not that valuable. If it's sentimental, yes, that IS important and should be treated as any valued item--whether a dress or photo or memento, etc. TSA and baggage handlers have jobs to do. Do they do them up to all our standards--maybe so, maybe not.
If you were buying rev tkts and not using crew labels on 5 checked bags, then you'd have grounds to make a fuss. But I wouldn't expect to get the dress back. There is still the possibility that it was a mistake when packing...
Addendum: Were you flying as a crew member? If so, you would be entitled to crew status. If your bag says "crew" and it's leisure travel, you can't expect any special status. You are actually jeopardizing your pass travel w/a fuss. Chalk the loss up as sad for the child. Your accusation about stealing from employees reads like misplaced anger. Move on and find something special to soothe the little girl.
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