Make new posts (any special message, anniversary dates and more)
Accept or reject friend requests
Update the profile picture and cover photo
Download an archive copy of the Facebook profile, which includes posts, photos and profile information.
For now, Facebook is limiting the legacy contact feature to the US only, but said that later they will expand it to other regions. The profile of the deceased person will also be made unique.
Have a look:
You can add a legacy contact to your account by opening the Settings tab, then clicking on More Settings and then Security. You will find “Legacy Contact” at the bottom of that page, where you can add the person of your choice. That’s it… you are done!
Source: http://anonhq.com/make-facebook-profile-immortal-legacy-contact/