When using the VLA for subarray observations, refer to the OPT manual for how to setup a subarray observation.
https://science.nrao.edu/facilities/vla/docs/manuals/opt/subarray-observing
For information regarding limitations to subarray observations, refer to the Subarray Observing section within the Guide to Observing with the VLA.
https://science.nrao.edu/facilities/vla/docs/manuals/obsguide/modes/subarrays