I have never seen a rewrite where there were no new features added to the software. Maybe the is part of the message, don't add features until you hhave replace

I have never seen a rewrite where there were no new features added to the software. Maybe the is part of the message, don't add features until you hhave replaced the old system. That sounds like a good idea but almost no one approaches it like that, which is one of the reasons rewrites often fail.