Legal Question in Wills and Trusts in Missouri

Open a probate estate and engage in a process

Known as the discovery of assets.

You might first check with the County where your father lived to see if an estate has already been opened. The will is just a piece of paper until it is admitted to probate.

Also, there is a statute that allows a person to obtain a court order requiring the production of the Will. I have done these with success. Good luck.

You don't say how long ago your father passed. That will determine the procedures available to you. If it has been within the past year, you can commence your own estate proceeding. This will force your sibling to come forth and present the will or be subject to your being authorized to wind up your father's financial affairs.