I read a post online by Jacob Singh about XML includes for solrconfig.xml. I have several indices with somewhat overlapping schemas and having to redefine these elements is not ideal. XML entity includes seems like a reasonable solution; however, the problem with Solr currently is that entity includes must include an absolute path file (which stinks for maintainance). It's fairly easy to modify the Solr code to tell the parser the context with which to resolve relative includes. I made this modification in Solr 1.2 to help in eliminating redundant schema.xml entries.
Is there any reason why XML entity include isn't currently supported? I can try and put together a patch if there is interest. Thanks Amit