changing value of xi:include's href variable during c

Hi guys!

I am using XSLTPROC and FOP 0.93 to compile
XML files. Because I use entities and macros within
the text, the compilation is a two-step process:

1) Creating an <filename>_online.xml file in which all
the entities and macros are processed and transformed
into XML-formatted text/inserting graphics.

2) Creating a <filename>.fo file out of the
<filename>_online.xml file. 

And now the tricky part: the xi:include mechanism. If
I call an XML file within another file via xi:include,
the compiler does not turn the included file to
<filename>_online.xml.

This is a problem if the called file contains macros,
for example a macro for inserting graphics. The macro
is not processed, and it does
 not turn to a
mediaobject.

What I would like to have is a kind of a
template/mechanism which will automatically substitute
all instances of xi:include href="myfile.xml" with
xi:include href="myfile_online.xml" during the first
step of compilation with XSLTPROC. 

Is it possible to create such?
 Please, advise...

Thank you very much in advance!!!!
My best wishes,
Nancy

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com