Kitt,
Make that Xcbl recordstructure as recordlist(publishable document) and so map the 3recordset to the structure above and publish it to Broker and subscribe the same publishable document(recordlist).
or else
In the subscribing service upon receiving the Canonical document then in the beginining steps use recordReference or documentReference and make that cannonical document as recordlist and so using appendToRecordList or appendToDocumentList(inputs map Canonicaldocument(record) to fromItem and map Canonicaldocument(recordlist)to ToList and output map the ToList to Canonicaldocument (recordlist) and make sure you drop the fromItem(canonicaldocument).So that this will not overwrite instead appending will takeplace.
HTH,
RMG.
#Integration-Server-and-ESB#Flow-and-Java-services#webMethods