vba excel - asynchronous workaround...code to shut down all macros using ontime

I've been searching around and haven't really found anything that fits. I know excel is asynchronous, but is there a potential workaround to shut all macros down say at a given time of day in order for an ontime macro to run. My excel document is used in an industry that operates 24/7 and doesn't stop until a project is complete. All data input is through udfs however, I need to run an input command at midnight every night. I've got the ontime coding for the command complete, but I'm still wondering if I have to build an ontime script into each form (~3 main forms that could be open at any given time) to save and close at midnight, or if that would even be the correct approach. Does anyone know of alternatives?

terribly sorry to bump this...but gonna try the western hemisphere if no responses I'll let it move to oblivion