Why can't I add outfits to my friends lookbook

Hi there,

I used to be able to add outfits on my friends page to their lookbook. This stopped a couple of months ago and I havent been able to figure out why and if I will be able to do this again? The old outfits I added are still there. Also some outfits listed are sold out immediately. How do I know when they come out so I dont miss out? Is there anyway of buying old outfits that sold out? Thanks