Two (2) qualifying patients, who both hold valid Identification Cards, are authorized to share one (1) enclosed, locked facility. In this case, it is unlawful to cultivate more than twelve (12) flowering marijuana plants, more than twelve (12) non-flowering plants, or more than twelve (12) clones in a single, enclosed locked facility, except when one (1) of the qualifying patients, as a primary caregiver, also holds a patient cultivation identification card for a third qualifying patient, in which case that primary caregiver is authorized to cultivate six (6) additional flowering marijuana plants, six (6) additional non-flowering marijuana plants, and six (6) additional clones for a total of eighteen (18) flowering marijuana plants, eighteen (18) non-flowering marijuana plants, and eighteen (18) clones in a single, enclosed locked facility. This provision shall not prohibit cultivating the maximum number of plants allowed in each category at the same time.