you can use the GLSyncSupportedTopology_Get to query displays that are available for genlocking. If you have for example a TimingServer configured you can pass this configuration as input to GLSyncSupportedTopology_Get and you will get a list of possible genlock configurations returned. The iNumSugSyncMode basically indicates the number of genlockable displays and the glSugSyncModes structure contains the display id and the possible genlock mode. this way you know which configuration can be applied on which display.