Tusla have published this guide for parents. 

This booklet is for parents of children aged 6 to 12 years who are being bullied and for parents of children
who are bullying others. It gives information on the reasons behind bullying and how you can help your
child if they are being bullied or are bullying other children

 

https://www.tusla.ie/uploads/content/Parents_Coping_with_Bullying_d3.pdf