How do you write a physical hardship letter to prevent a movement of an instate inmate?

Be plain, simple, and sincere. Be detailed in the reasons it would be a hardship for the family if the inmate is moved. Finally, throw yourself on the mercy of the DOC, because it is entirely their purview whether the inmate is moved or not. Even in the most difficult situations, it is unlikely any letter will change their course due to facility need and security issues. If you have contact with a state other govermental body representative, enlist their assistance. Other governmental agencies are the only bodies recognized by the DOC as legitimate, and their support for your cause is your best hope.