Many times in BizTalk land we work with Schemas that are nested and have several related
Schemas that are Imported from URL locations etc.

When you include these schemas and deploy to Production, you find out that the BizTalk
server doesn’t access the Internet directly. Hence all the schema Imports fail.

You’ll then go and try hand edit the Imports, downloading the referenced Schema and
try and Mash up something that refers to local files and no URL based Schemas. It
may or may not worktill the next update

I recently came across a handy set of free tools that take all the pain out to do
with Schemas ->

Help Line

Which has Xml Schema Lightener, Xml Schema Flattener

Another very handy tool not to leave home without.