XP hasn't seen the dc's in over a year and refused to see them at a contact centre. He pays maintenance through the CSA.
I don't have official custody of the children as XP didn't want to bother seeing them and never put up a fight. They have his surname though.
When DS starts school next year does it mean that XP could turn up and collect DS and be able to take him and the school can't do anything about it? 
Obviously either me or my mum would be picking DS up but I'm going into a 'what if' scenario and wondering if this means I need to get a solicitor involved to get official custody so the school will be able to stop XP taking him.
Off to do bath / bedtime but back later! TIA.