Should this dog be put to sleep?

My grandparent's dog bit my three year old cousin yesterday because she got too close to her. This is not the first time this dog has bitten kids. She's bitten a five year old and a two year old (on the face too), not to mention several adults as well, even her owners. My aunt and uncle say they won't press charges, nor demand that the dog be put to sleep but you'd think my grandparents would have her put to sleep anyway to prevent anymore incidents from occuring. They have owned this dog five years now and she has not been abused since she's been here. She might have been abused by her previous owners but after five years of good treatment, there really is no excuse for her to be acting this way. Each time she's bitten the kids, it was for no other reason that them getting too close to her, and not while she is earing either. And no, you can't say "keep the kids away from her" because the kids play in the yard where she is and she doesn't seem to have sense to stay out of their way, she'll come right over to the area where the kids are playing. It's like she is daring one of them to come over. This last incident happened when my grandmother was sitting on the porch with my cousin standing next to her chair and the dog came over too. When my grandmother tried to shoo her away, she (the dog) stepped backwards toward my cousin and my cousin lost balance and accidently leaned against the dog and the dog turned and bit her upper arm. My grandparents are unwilling to have the dog put to sleep but one day she is going to bite someone who will press charges.