Can an isolated incident of inadequate supervision be considered child neglect if it was an accident? Part 2?

I went to work at 4 am and left a 7 week old on my bed b/c i knew she couldn't move and her dad would be up soon and her grandmother would watch her once he left. Grandmother looked in on her at 5 and she was still asleep, so grandmother went back to bed. Dad claims he didn't look in b/c he didn't hear her and went to work at 7. I got home at 10:30 and found baby between the bed and wall. Took her to ER b/c I was freaked out and they called DHS. Local Police dropped investigation. DHS is now trying to put grandmother on Child Registry for neglect. I was an isolated incident that was a true accident. Our apartment is small and you can hear baby cry in next room where grandma was. But since she was between bed and wall no one heard her. I don't want grandmother on registry or dad in trouble. I secrectly think dad fed her and turned her around and put her closer to edge of bed and just doesn't say anything. Grandmother wouldn't lie to me and she says she didn't fed her, but someone did, and someone moved her facing opposite direction. Attorney is vague about what will happen. Baby is now 8 months and thriving. Is there something that mandates what you have to do to get put on the registry? I'm in AR, please advise!