I am so sorry for your loss and for all of this.  The 5th sibling needs to seek help from an attorney in your area as soon as he or she possibly can.  It appears that the executor is also the trustee of the trust and that he may indeed be abusing his powers under the law.  From what I can gather it is not like the executor is stating that the 5th sibling was disinherited and gets nothing.  He is stating that he is refusing to distribute to the 5th sibling.  A Will is a public record once it is filed so anyone can go tot he probate court and review it.  The trust is another story. But as beneficiaries all should have received copies of both when the probate process started.  Someone needs to check this executor and demand an accounting of the estate.  Good luck.