Lauryn, I am sorry about what you and your family are going through, it is a horrible place to be "NOT KNOWING" I am one of the members here that had a missing person in my family, I wouldn't wish it on anyone. I hope yours turns out better than mine.
Social media can be great tool. People always say things, some helpful, some not, some offensive. The worst thing you can do is get defensive and respond to them, you are just provoking more backlash. I saw it on the Sussex Police FB page. My advice to you: do not respond to any of it. Just read what the helpful people suggest or new ideas, take note follow thru. It's upsetting enough to go through this, stop making it worse by feeding into peoples BS don't lower yourself to it. You have to accept it's part of social media. Unfortunately you get the bad with the good, but there are many more concerned and helpful people out there than the jerks. Concentrate on the good tips and info you get and put your energy into that for a resolve.
As far as web sleuths go, it's people just doing that "sleuthing" throwing around ideas for discussion on the forum. It doesn't mean that is the case with your Dad and brother, members are just kicking it around. I am not going into all the successful resolves that web sleuthing has had, but there have been plenty. In addition a lot of contributions i.e. Carl K, the artist that has put faces to the unidentified which gave them their name back. So don't knock this crazy hobby of ours "sleuthing". It pays in ways that you will never know. Perhaps for me I feel like I am trying to help and giving back after what I went through. Or to connect with others that understand and have gone through the same experience as I have.
I wish your family the best in finding a resolve in this very soon, as well as a great outcome. Never give up, always have hope without it, you have nothing.
