Bit of background - DS is 3.3, his dad is named on his birth certificate. Myself and DS lived with my parents till he was 18 months old, it was around this point that myself and his father split. It's been a bit on/off since then, but is off for good now.
If I should die, would custody automatically go to my ex? He sees him once every two-three weeks. I'd be happier, and I know that DS would be happier, if my parents became his legal guardians as obviously he is a lot closer to them. We spend every weekend at my parents.
Is there something legal I can complete to stop my ex getting full custody in such an event? I'm not being spiteful, I'd just hate it if DS was uprooted and had to live with someone he hardly knows as opposed to his grandparents who he loves. My ex is also a regular cocaine user, and still lives with his nan and heroin-addict brother.