A port closure system for use with a fluid container having fluid ports includes administrative and additive port closure assemblies. The administrative assembly receives a piercing pin and includes an administrative housing which seals closed one fluid port. A sleeve extends from an interior surface past a base surface in the administrative housing. The sleeve has an upper portion and a lower portion, of differing diameters. A cap assembly mates with the administrative housing, sealing the interior surface of the administrative housing. A removable cap provides access to the interior surface. The additive assembly receives a needle and includes a reseal housing which seals closed another fluid port. Another cap assembly mates with the reseal housing, sealing an interior face of the reseal housing. Another removable cap provides access to the interior face. A reseal element is mechanically retained between the reseal housing and cap assembly.