Is my son entitled some of his fathers lump sum?

my 1 yr old sons father is being a right tos pot at the moment, i dont live with him he lives with his mum and dad, he is 34 though.hmm... he has just got a lump sum payout of 3,000 last month from his grandad who died last year. the trouble is he is a keen gambler ( i know im working on him for that) jackpot machines and horses, but in a month hes gone from 3,000 to 1900 in a month. i know exactly where its gone, i dont need to ask him. the trouble is he only gives me the cmp im entitled to and not a penny more, i just wondered if there was any law out there saying that our son was actually entitled to some of that money without him flitting it all away? ive got another daughter from a previous marriage (thank god im not married to this one, i learned my lesson the 1st time) and when we got divorced we had to sign something called a clean break order, which was basically if either of us (me or my ex husband came into any money we wouldnt be entitled to it), but it doesnt apply to any children we have together, they were still entitled to a percentage. So i just wondered if the same rule applied for my boyfriend and our son? please help, or guide us to some info websites or something where if the worst happen then at least i have a leg to stand on with my son. i only want whats rightfully his, if it is xxx