\defineXMLpush actually makes its definition when the pushed element
occurs. When a parent element defines a group, then the pushed element
is not visible outside that group. In \TeX\ this problem is usually
solved by doing a \gdef. Perhaps this problem can be solved in the
same manner, by providing a \gdefineXMLpush.

See attached example.

-- 
Simon Pepping
email: spepping@scaprea.hobby.nl