Father in law worried about leaving money to gambling son - advice?

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My lovely father in law is updating his Will currently, and is worried about leaving a chunk of money (potentially, depending on any care home fees etc!) to one of his sons, who is a gambler.
I've had a look around online for advice, but haven't found any solutions yet.
Does my father in law just leave my brother in law his portion of any money, in the knowledge he might well gamble it all away? It is a 'kind' or fair thing to do to a gambler? Should he leave the money to another son to look after on the gamblers behalf? Is that going to cause resentment?
We're not talking millions here, but still possibly a big chunk.
Brother in law has told us of his addiction, and says he has it all in hand and is repaying his debts. (We don't know for sure, obviously). But even a gambler in recovery might relapse if given money.
Can one leave money to someone is some sort of safe trust in this situation? Has anyone here been through this?
Help!

He either leaves him the money or he doesn't. There's no middle ground.

Yes he can put the money in a trust but theres no guarantee that he won't gamble the money away when the trust gives it to him either!

Does the gambler have kids? Maybe just bypass the gambler and give the inheritence straight to the kids (if they're adults, obviously)

Does brother in law have dc? Could his share go to them instead? This is what my parents have written in their wills.

Brother in law is sadly single, so no kids of his to pass anything on to. I wondered about his brother managing his share, and giving a certain amount for specified things - eg buying a different house, car, holiday etc, or at the very least only giving it out in smaller chunks?

Give him one 5th

Let him do what he wants with it, and make his own way in life

@RudbekiasAreSun I'm curious why one fifth in particular?

Generally, I'm surprised the gambling charities I contacted couldn't offer any advice on this, it can't be an unusual scenario. 🙁

Leave brothers share in a discretionary trust in dads will managed by your Dh in consultation with his brother. Is quite common dm me if you like

I wouldn’t leave him anything- it would be like leaving a crack addict money- they will burn through it all.
( Know someone who spaffed the value of a London house up the wall on crack -
addiction is a terrible thing.

If a house could be bought on his behalf that he couldn’t sell- that would be better.

In Australia we have testamentary trusts that you can leave a trustee (such as your husband - assume he and gambler are brothers) in charge of the gamblers money but they are still the beneficiary of the money - they just need your approval to access/utilize the funds. Would that be possible in your country?

Would there be enough to buy him somewhere to live, that wouldn't be owned by him? The other brothers could own it, and he would have the right to live there for the rest of his life?

Sounds tough
I am not a lawyer but I understand that if your FIl wishes to leave him out of the will or leave him a lesser portion etc it is a good idea to state why as well.
A lawyer would advise the best way to do it
Morally I think just leave him to it but then if/when he burns through it will your DH be expected to help?