Can you contest a will or slow down grant of probate if?

If the sole beneficiary is a heroin addict and has been put on two years rehabilitation program?
The family is worried that everything this bloke's mum worked for will end up blown away. Is there any way that the family can insist on the estate to be put in trust and to rewieved later when he is cleaned up?

The executor is a solicitor, is one of those that drew the will in first place, but he is executing the will as per wish. He is not emotionally involved. As for the remark, every time a will is mentioned you get the raised eyebrow, but, I didn't mean contest in a way that he doesn't get what the will says, but get it when he is able to make clear decisions. Right now whit his state of mind, having large sum thrown at him is not very wise thing to do. As a drug addict who never had a job we fear that in two years he will be pennyless.

Every will has an executor, that's the person or persons nominated by the deceased who excepted the responsibility of executing the will in a formal legal manner.

An executor can stay the power of execution, (freeze the assets of the will). They have no power to change the contents of the will.

It would be then up to the beneficiaries to challenge that decision in court. A judge has the power to force the wills execution or side with the executors decision and place whatever conditions he/she sees fit on it.

My sister has two children, but only one of them is in her will and she wants it to be water tight, hence the power of executor has been fully explored. Similar situation, just the would be deceased is planning ahead.

If you have reasonable cause (and it sounds like you do) then the family should be able to contest the Will. If that's not possible the Executor should be able to apply to have the money, property etc. held by the Solicitor until the sole beneficiary has cleaned up their act or until the end of the two years rehabilitation. Either way, the family involved should really get someone from the family to contact a Solicitor. Probate generally takes anything from six months to two years to complete and in a situation like this where there are good grounds for debate the Probate is likely to last a long time anyway.

Not in the US; you'd be better advised to pursue getting him a legal guardian/conservator than trying to contest or delay probate

in theory yes.

But best to seek legal advice pronto.

also ask about a power of attorney and a guardianship order

Mind Your business. Out of interest, are You in His family?

no