On Form Exit doesn't run when using Escape. We don't run code when you are trying to leave without saving changes. There is a NotifyForm flag to prevent the form from closing and there are functions like @FormWillClose and RunExitProgrammingOnCloseForm(), but it might be tough to get everything in the right place. Some experimentation would be required as to whether it works as you want when placed in the Parent Form or in the Subform.

Why are people not allowed to leave if they are in a subform?

putting NotifyForm(6) in the parent, and then NotifyForm(-6) in OrderSubmit and OrderDelete buttons worked to prevent the form from being exited with the escape key (thank you!).  But I would love for the mistried <esc> key to pop a MsgBox instructing the user to, in effect, fish or cut bait.  I'll dig a little.

It depends on the "instruction", though, in general I wouldn't assume any inheritance from form to form or form to table. It is much better to be explicit and tell each form exactly how you want it to behave. Some "instructions" can't help but be inherited, others will be ignored as inappropriate, some will be interpreted to be appropriate for a form or table - and so, act differently.

In general, I believe that you should reconsider designing around the idea that people can't leave/cancel a form. They will always be able to do so. If you obstruct the easy paths (hitting Escape), they will take the less desirable paths (killing the process). We cannot entirely eliminate their ability to whack any running program, including Sesame. If you give them no alternative path, you will have to deal with increasingly extreme situations.

If your programming is causing a "commit" of any kind before the user has submitted a final top-level form commit, you should either find some way to hold off until that user is certainly not canceling, or find some way to "roll back" the lower level information. You might consider including a flag in that information that indicates that it pending a higher level commitment on the part of that user. Set that flag for all subrecords after the parent record has been committed. Otherwise, check for clear flags occasionally and eliminate those subrecords, either be removing them from a result set in use, deleting them, or ignoring them in calculations.