Resolution for error 9506 in data replication during DDL changes

In our environment we are using IIDR (CDC) to replicate data from various DB platforms (Source - Oracle, DB2 LUW, AS400, DB2 ZoS) and target the replicated data into Datastage Flat File agent. The data written into flat file will get matured every 1 Hr. Both the source and target agents are running remotely in a dedicated CDC server and there is no control on the DML or DDL changes happening on the Source end.

We have automated the schema evolution (DDL changes) end to end using a set of framework job which runs periodically and does the following:

1. Whenever the CDC subscriptions fails due to DDL error, the target bookmark is backed up.

2. Update the table definition with latest structure in the CDC repository.

3. Set the source bookmark using the target bookmark fetched from step 1.

4. Start the subscriptions.

The above process works fine for most of the scenarios, but we are getting error while restarting the subscriptions in some scenarios. The error code appearing is 9506. When we analysed further it looks like whenever the DML has happened just before the DDL, the DML will be written into the flat file but before it matures the DDL will make the subscription fail. The target bookmark will not move since the file is not matured and when we set the target bookmark into Source and start the subscription CDC will again start reading the DML happened before the DDL, but the latest structure updated in the CDC repository may not match with the DML structure as per archive log. We have raised case with IBM but their suggestion is not perform DML before DDL but in our environment its not possible to control it as data sourced from multiple sources managed by various teams.