Your DD should look at her university's examination regulations. They will be easily available on the University website.
That said generally (but this can be different with each university) generally, when mitigation is applied for, there is a separate meeting - a Mitigations Committee meeting - to consider each case individually.
At my place, this is done at a Faculty level, so decisions are fair & transparent across the broad cohort. Final decisions are made with anonymised data, in a 2-part process.
1st part is that the student's case for mitigation is considered. A decision is made about level or category of the difficulty experienced so that it's proportionate (so death of a distant cousin treated differently to death of a parent etc etc). These categories are then connected to the student's ID number, so the 2nd stage is anonymised.
At the 2nd stage, and involving different committee personnel, we consider the students on an anonymised case by case basis. We look at the assessment result (eg essay mark, exam mark, presentation mark etc) and look at when the event or misadventure etc occurred, and then make a determination of whether the student's mark was affected. That's done by comparing that specific mark with the student's general run of marks across their degree.
Now, the point of explaining all this to you is that what happens quite often (more often than students thin, actually), the student's assessment has not been materially affected.
It is more rare than not that the misadventure/illness/ personal circumstance alters the class mark (which has a range of 10 marks in the 2, i, 2, ii, and 3rd categories). So, it is actually mathematically unlikely that shifting a mark for a specific assessment item (eg one exam, or a specific presentation) will affect the overall class mark.
The individual may have felt awful, but actually, they're as likely to have performed pretty much at their usual level, than not.
The students who are much more affected are those with ongoing chronic health issues, or dealing with ongoing difficult personal circumstances. Although mostly, those are the students who move heaven & earth to do as well as they can - I have sometimes had to almost force students into seeking mitigation in those circumstances.