My four year old sometimes instegates situations with the 2 year old in my care, eggs him on, and then tattles on him when he inevitably pushes, hits, etc. What I have found really helps is making him my special helper with the job of making that specific child happy...and every time he does something that makes him happy, I praise him up and down and he soaks it up like a sponge and wants to do more. Also, ignoring can work because it is an attention getting behaviour...even if the negative attention ends up being pointed toward whoever they tattled on, it is like entertainment and they get satisfaction out of it. So if you shrug it off and change the topic abruptly, it takes all the fun out of it...ex "Oh really, hey who wants to play with playdough?" I don't have much advice for the 10 year old as I don't have kids in my care older than 4 and my older son was not like that at that age. Good luck!