Enforce Change Order while performing Item Category Assignment

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We have a requirement to enforce Change Order when someone creates/updates Item Category Assignment. If we add/update Item-Category assignment on an Item and try using 'Save As Change Order' option on Manage Item UI, system does not recognize any changes done on an Item and does not allow to Save the changes made on Item categories on a Change Order. 

We tried using Item rules of type validation but could not find any function to check the changes done on an Item-Category Assignment and enforce Change Order. 

Please let us know if you have worked on a similar requirement.