Bobbi Kristina’s funeral will be yet another family face-off -- the Browns are on high alert and worried the Houstons will sneak a photo of her dead body ... and sell it. Sources close to the Browns tell TMZ ... they fear a repeat of what happened when Whitney Houston was laid to rest in 2012 ... when a photo of her body, in her casket, was snapped and ended up on the cover of a magazine. Since the Brown family was persona non grata at the funeral ... they believe someone from the Houston side was behind it. Our sources say the Brown family plans to band together and stand guard ... and their eyes will be trained on the Houston family. Pat Houston is managing the funeral, so it has all the makings of turning real ugly, real fast.