The formation, evolution, and interactions of a closely spaced pair of coflowing rectangular synthetic jets are investigated using particle image velocimetry. The dynamics of the combined jet is determined by the interactions of the counter-rotating vortex pairs that form each jet. These vortex pairs are formed along the long edges of the orifice of each jet by the time-periodic motion of a diaphragm that is mounted in a cavity underneath the orifice plate and is driven at resonance. It is shown that the phase between the actuation waveforms of the adjacent jets affects the relative timing between their blowing and suction strokes and consequently the formation of the vortex pairs that synthesize each of the jets. These phase variations also lead to controlled vectoring or bending of the combined jet toward the orifice of the jet that is leading in phase and can be varied dynamically on time scales that correspond to the actuation period.