What rights do children have?

[AnonymousMummy123]

Sorry if this is in the wrong place I wasn't sure where I was meant to post it.
So I'm really confused over the rights of a child, my partner has 4 children from a previous marriage, last summer the oldest told his mum that he wanted to live with daddy and didn't want to see her anymore. To which she dragged him by his wrist into her house, bruising said wrist and locking the door so he couldn't get out, rang the police on him for trying to kidnap their child (which he wasn't this happened as he took the kids to her home) and then took him to court making up abuse claims saying he used to beat her and shouldn't be near the children (they had been apart 3 years at this point and she had never mentioned that to anyone before nor tried to stop him having the children because he's abusive until 1 asked to move out)
In court the judge dismissed abuse and instead of taking them from him completely like she asked awarded him with shared custody instead of just weekends. The problem is the oldest who is now 9 still crys every week begging not to be made to go back there. He asks why we won't let him stay, he gets annoyed when we say theres a court order in place stopping him from being allowed to then crys mummies right you just dont want me. I've read things that courts only let children choose a parent full time before they are 12, is this true? Or is there anything we can do, he's clearly stressed and upset about leaving, there is clearly something wrong, and he's feeling rejected every time we force him to go back there. We hate seeing him so upset, so hurt but we don't have a clue how we can help him. Any advice would be much appreciated

Has he said why he doesnt want to go there? Without the knowledge of why the child is saying these things, it's hard to give advice. If there are safeguarding concerns then Dad needs to speak to someone and get an emergency order in place. If it's more to do with preference then just reassuring the child is the best option. Reassuring him that he is loved. That his mum loves him too and it's important that he sees mum and dad. Reassure him that you will always be there for him and you arent going anywhere. Tell him you dont know why his mum is saying that you dont want him but that is not true or else why would he be there with you right then if you didnt want him. From the history, it would seem that mum doesnt want to help calm the situation but she is ruining her own relationship in doing so

We have asked why but he just refused to say anything other than crying and begging to stay. We worry about safe guarding issues but the other 3 seem perfectly happy about going back to her, it's just the eldest who gets incredibly upset about it. The second eldest has been upset a few times recently about coming here and when asked why by his dad he broke down crying and said well mummy told us you dont love us or want us so why would we come where we aren't wanted. To which we try to reassure them that they are wanted. And then he calms down and is again happy to be here for a little while, so it's something shes drumming into all of their heads, no idea why she'd be that cruel to them, but even with hearing this the oldest begs to stay... I just hate seeing him so upset and no knowing how to make it better.