What should happen next if nobody will cooperate on choosing an executor or other fiduciary?

The best choice for a fiduciary is generally a person who is trustworthy, detail oriented, available, willing to serve, and steady when conflict arises. When the legal documents are reviewed, the first practical step is to identify which document, title, or court appointment currently gives someone authority to act. As part of the legal review, co fiduciaries can provide checks and balances but can also slow decisions if signatures or agreement are required. Because probate, property, trust, and family rules vary by state, a local attorney should review the governing documents and current court or title status before anyone takes an irreversible step; that can affect both the process and the eventual outcome.