What is the procedure for performing Umrah on behalf of one's deceased father after having performed Umrah for oneself?

You perform Umrah on your own behalf, commencing your ihram from the Miqat. Once you have completed it, you proceed to Tan'im or any other location outside the Haram area (حل) and assume ihram for an Umrah on behalf of your father. You are not required to return to the Miqat to assume ihram for him.