At the end of a trust of if a trust fails

I find Testators of Will Discretionary Trusts don’t like including their default beneficiaries as beneficiaries in case a Trustee favours them over other beneficiaries.

Is it acceptable to us this instead:

At the end of this trust, or if for any reason it should fail, my Trustees will distribute the Trust Fund equally between my brother John Smith and my sister Julia Smith but if the above provisions should fail, my Trustees will distribute the Trust Fund absolutely to [charity name and number etc].

It would be a poor Will if produced that way, what happens if either the brother or the sister dies? Does the estate pass to just one of them, or partly to them and partly to the charity?

Thanks - I stripped it out to for the forum purpose just to keep it simple about the concept of ending the Trust rather than the full text of it being per stirpes, and if one sibling dies the other benefits before the charity etc etc.

Hi, I always suggest to the client to add as their final beneficiary if there is a cataclysmic event that it goes to the Charity(s) of their choice to stop the Exchequer receiving it! Before that, it’s split or whatever they want with various fallbacks, issues, other family, so hopefully it never ever gets to the charity.