I hope I understood you right: Probably the question would be what is required by the applications using your drop copy session and not how to disseminate any possible information by chance.
A.) a typical back office session which only cares about trade information (msgtype 35=AE) for settlement and middle office CCP purposes or
B.) is it really crucial for those (drop-copy) receiving application to update information about any order status change
1 right after it happened or
2 at start of or
3 end of
trading hours ?
2 and 3 could be achieved by receiving sell side initiated restatement messages (150=D) or by DoneForDay messages in a batch driven mode during a short pre- and post trade period I guess.
The effort to achieve 1 may be possible by making the following tags mandatory:
102 in 35=9
103 and 378 in 35=8
373 in 35=3 (technical/session rejects)
But also let’s keep in mind: As long as a (Cxl) Request was rejected the request had no influence on the order status and it has not changed. Even for an order that had become invalid (“too late” to Chg/Cxl) before the request was received and processed (due to message crossing).
Do your non-trading (=drop copy session) applications require updates on order status and even then:
If that was true do they really bother about rejects and the reasons and the request content ? This should be clarified in deatil beforehand I believe.
About Restatements and Drop Copies also refer to Hanno’s document about “Recommended Practices for the use of FIX by Exchanges Phase” from 2007 ready for download here in “https://www.fixtrading.org/recommended-practicesguidelines/”. Probably you are already aware of it.