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Without seeing the original trust document, usually in these situations, if the beneficiary does not meet the requirements of being sober, then the beneficiaries 50% devise, remains in trust until he meets the requirements. The provision does not mean his 50% distribution is forfeited. For example, let's say you die and he does not meet the requirements, then his distribution will remain in trust controlled by the trustee you have appointed. If 5 years after your death he now meets the requirements, then the trustee can make the distribution.
That is still a possibility depending on whether that language is in the trust
In order for John to get Zero your trust would have to state that failure to be clean and sober results in a forfeit of his share of the Trust
You may scan and attach the documents.