How is my nephew doing this?!?

My nephew likes to create fake accounts and come into my lives being disrespectful to people and just talking smack for no reason. He is 16 and is able to go live but the problem is I keep banning his fake accounts but he has been able to copy someone's information and account details of other people so there will be 2 of the same person name in my live with same picture and all but one has alot of followers while the other one has like 2 or 3 very low which makes it the fake one but now he is coming to my lives and inviting himself into a box without me even sending a invite or accepting anything im not even touching my phone like how the hell is he doing this and how do I report him cause all he does is cause issues with me and its harassment at this point. What do I do! I reported many of his account and nothing happens