A system (210; 520; 624) for delivering neurostimulation to tissue of a patient using a stimulation device (212; 312; 512; 626; 1312) and a plurality of electrodes (211; 311; 511; 631; 731; 1044; E1-E16) and controlling the delivery of the neurostimulation by a user, the system comprising: an external programming device (213; 413; 1413), the external programming device (213; 413; 1413) comprising: a programming control circuit (419; 1419) configured to program the stimulation device for delivering the neurostimulation through one or more electrodes of the plurality of electrodes according to a stimulation configuration specified by a waveform parameter set defining a waveform of the neurostimulation and an electrode parameter set defining an electrode configuration of the neurostimulation; an external storage device (418; 1418) configured to store one or more neuromodulation relationships and one or more computational models of one or more neural targets, the one or more neuromodulation relationships each relating one or more candidate stimulation configurations to the one or more neural targets, the one or more candidate stimulation configurations each selectable to be the stimulation configuration for programming the stimulation device, the one or more neural targets each specified by a target parameter set; and a user interface (414; 1414; 1514) coupled to the programming control circuit and the external storage device, the user interface including modulation control circuitry (450; 1550) configured to: obtain relationship information; add or adjust a neuromodulation relationship of the stored one or more neuromodulation relationships by performing a simulation using the obtained relationship information and one or more computational models selected from the stored one or more computational models of the one or more neural targets; obtain two parameter sets selected from a group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set; and determine the other parameter set selected from the group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set using the two obtained parameter sets and a neuromodulation relationship selected from the stored one or more neuromodulation relationships. an external programming device (213; 413; 1413), the external programming device (213; 413; 1413) comprising: a programming control circuit (419; 1419) configured to program the stimulation device for delivering the neurostimulation through one or more electrodes of the plurality of electrodes according to a stimulation configuration specified by a waveform parameter set defining a waveform of the neurostimulation and an electrode parameter set defining an electrode configuration of the neurostimulation; an external storage device (418; 1418) configured to store one or more neuromodulation relationships and one or more computational models of one or more neural targets, the one or more neuromodulation relationships each relating one or more candidate stimulation configurations to the one or more neural targets, the one or more candidate stimulation configurations each selectable to be the stimulation configuration for programming the stimulation device, the one or more neural targets each specified by a target parameter set; and a user interface (414; 1414; 1514) coupled to the programming control circuit and the external storage device, the user interface including modulation control circuitry (450; 1550) configured to: obtain relationship information; add or adjust a neuromodulation relationship of the stored one or more neuromodulation relationships by performing a simulation using the obtained relationship information and one or more computational models selected from the stored one or more computational models of the one or more neural targets; obtain two parameter sets selected from a group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set; and determine the other parameter set selected from the group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set using the two obtained parameter sets and a neuromodulation relationship selected from the stored one or more neuromodulation relationships. obtain relationship information; add or adjust a neuromodulation relationship of the stored one or more neuromodulation relationships by performing a simulation using the obtained relationship information and one or more computational models selected from the stored one or more computational models of the one or more neural targets; obtain two parameter sets selected from a group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set; and determine the other parameter set selected from the group consisting of the waveform parameter set, the electrode parameter set, and the target parameter set using the two obtained parameter sets and a neuromodulation relationship selected from the stored one or more neuromodulation relationships.