If you are keeping data in a Pharo image then you could just save the image instead of using STON. Alternatively, you could model your data in an Application class with three instance variables: theaters, movies, and events. Then you could dump the root application object and STON should preserve the relationships (I expect). I prefer this model since it allows me to create a test object that encapsulates all the data in one place (even if it is referenced from a class variable).