  We demonstrate that asymmetric 3-port devices can be used to design a
multi-functional set-up operating as a symmetric combiner and splitter at the
same frequency. For a concrete implementation of the proposed
multi-functionality protocol, we employ a resonant acoustic 3-port device
operating in a subwavelength regime, showing splitting/combining abilities with
nearly perfect transmission in presence of losses, induced by the interactions
of the system's resonances. Finally, as an extension of the 3-port
multi-functionality concept, we propose a new type of 4-port networks,
consisting in an assembly of 3-port unit cells with combining/splitting
properties, capable to achieve various wave guiding features with perfect
transmission depending on the phase of the inputs.
