Hi Khalil,
I believe there is no option to add the sort order bar when you retrieve information by association.
See this document below.
https://docs.mendix.com/studio8/page-editor-data-grid
Hi Khalil,
What exactly do you mean?
When inserting a DataGrid there is a Sort bar already in this DataGrid.
Double click on this bar en select the sort filter. :)
Good luck!