there could be many options.
1. Use a java mapping to break the message into smaller records and then create a target xml structure.
2. Use an xslt map, to create a new node once a counter variable reaches 200. then use Multi map.
3. you can create a UDF which will create multiple target nodes, based on the number of records. In this case also, you have to use multimap.
Regards,
Gavaksh