I hope this message finds you well, present circumstances excluded. This can be a tough issue because there is no law that states a person has to file their will with any court or repository while they are alive. Perhaps the best way to find a secondary will is to request in the country court in which the person that passed away and in which the current will is being probated that Subpoena's be issued to those that may have knowledge of an additional will to produce such document if it exists or sign an affidavit swearing that there is no other will.

In other words, the only will currently known about will have to go through the court system for the court to sign off on it. This is called probating the will. If the will is not being probated and you are an interested party, you can petition to the in the county in which the deceased resided to probate the will. If the will is already before the court, you can make what is called an entry of appearance (which formally announces your interest in the will) before the court.

You then request that the court issue subpoenas to those people that may have knowledge of an addition will to force them to produce this information or swear and attest that such a second will does not exist.

In summary, the best (and perhaps the only) way to find out if there is another second will is to have the only other will probated before the court and request that the court issue subpoenas to people that may have knowledge of another will to either produce it or go on record that it does not exist to their knowledge.