If the list is just for visual purpose then you can create a non-persistable entity and associate it to the parent entity, create the number of non-persistable objects per list item and set assocaiton to the parent object. In the page add a dataview as context and place a list view widget within the data view and retrieve list via association. There might be better ways of doing things depending on what you are trying to achieve, above mentioned is just one of the example. I would recommend you go though Mendix learning paths (if you have not already did so).
Hope this helps!