Enrich by Inclusion
From Documentation
This documentation is for an older version of ZK. For the latest one, please click here.
If you prefer to rewrite a portion of an existent page, it might be better to put the rewritten portion in a separate ZUML file. Then, you include the ZUML file from the existent page. For example, you could use jsp:include if JSP technology is used.
<jsp:include page="/my/ria.zul"/>