I have to agree that the above statement about grandparents making up false accusations is true many times. I have seen in custody battles that all too often that grandparents simply intervene and take sides without listening to any facts.
Also the kids are old enough to honestly answer if they were being abused. I am thinking the grandparents got custody due to lies and when it was time to turn the kids back over, the parents probably planned to stop all contact with them so they g-parents took off. Nobody sane or credible would make a threat against the grandkids.
RIP Liana Sandoval, Kelsey Briggs, and Baby P.