Mrs Pinkerton, who now lives in Bunbury, Western Australia, said her mother in Rotorua had told her about the damage to Madisyn's grave just a few days ago. She said the incident had happened about a week ago, around the same time as the anniversary of Madisyn's death, but her mother had avoided telling her straight away because she knew it would have been difficult for her.
"It's hard enough to lose your child, so hard, but to have something like this happen, it's horrible. It just makes it all so much harder."
Mrs Pinkerton's father's remains had been buried in the same grave site as Madisyn and to see the joint grave site destroyed was a an emotional blow, she said.
Mrs Pinkerton said she had no idea who was responsible for the damage, but said whoever it was had no conscience.
"I just don't understand who could do this and why? Destroying a baby's grave, a father's grave too, it's just heartless, they have no respect."
This is not the first time a grave has been vandalised at the Sala St cemetery. In October last year, the grave sites of up to 50 children were damaged by vandals.
She said no mother or father deserved to see their children's graves destroyed and something needed to be done to stop this from happening again.
Mrs Pinkerton said her mother didn't report the incident to police at the time because she didn't want her daughter finding out.