12.  Where the Sheriff has to remain in possession of movable property for more than 14 days, the execution creditor must before or at the end of the first 14 days of the Sheriff keeping possession, deposit in the Registry, if the Sheriff so requests, a further sum of money to provide for the costs of execution for the next ensuing 14 days and must continue to make such deposits in advance before or at the end of each successive period of 14 days so long as the Sheriff continues in possession.