Hi Again,
something i have done that might help as a work around is setting a new Object called “Due Date”
of course you can call it what ever makes sense to your requirements, e.g next step …
then you can create date based triggers e,g when its goes 1 m over this then do … send email/close send email
i hope i understood your question right, this is then not changed on replies of course unless you set a trigger for it
Thanks