Set priority between possible errors in an Ad-Hoc SubProcess.

I've been digging for an answer to this in the BPMN Documentation and tutorials around the web but couldn't find one so far.

Situation is as follows:

1. - I have a 'Check Order Status' ad-hoc subprocess, which itself contains tasks such as 'Check if order will meet the delivery deadline' and 'Check for other problems';
2. - In case the order suffers a delay, the subprocess is interrupted to trigger a 'Ask department in charge for new deadline'. If the employee finds out the order had a problem (i.e. the order was cancelled for whatever reason), they start a refund process;
3. - Both 'Order has suffered a delay' and 'Order had a problem' are error events attached to the subprocess;
4. - The problem lies here: If an employee identifies a delay before a problem, it will inevitably trigger 'Order has suffered a delay' event and will never be able to spot the existing (fatal) problem, which is much more severe than a delay. The subprocess MUST be ad-hoc - since tasks therein cannot be sequential.

My proposed solution would be to set some sort of priority between the error events... but I'm not really sure how I would do that. Otherwise, I would have to turn 'Check for problems' and 'Check delay' into a sequential flow, but that would be much inaccurate.

Could you guys give me some sort of light?Thanks in advance,Dan.