If you have students who come from other schools, such as for music lessons, you can log their purchases in Arbor.
Students must be enrolled in your school to be able to purchase School Shop items. In Arbor, students can be enrolled in your school without attending classes and appearing in lesson registers. All you need to do for your external students is follow the instructions in this article: Adding guest students and changing enrolment modes
Please note that adding guest students can skew your report numbers. For example, they will be included in your school Dashboard Statistics and could be counted twice on the MAT MIS if they come from another school in your MAT.