Employment Tribunals are brutal. Your daughter should prepare to be interrogated, almost like a court of law.
The burden of proof requirements differ from a criminal court, but they still do require a "reasonableness" assessment.
I have been to ET as an Appellant Manager (in other words, I upheld a messy dismissal of an employee). The case I was involved in had nothing to do with diabetes. I was under questioning for most of a day. It wasn't fun, but I had acted appropriately and prepared well. The findings went in my employer's favour.
If your daughter hasn't already, she should seek whatever advice she can find, via a union, ACAS, Citizen's Advice or whatever. She WILL need support in that room. Her former employers, if they are if any size will likely have instructed Barristers to argue their side of matter.
Please, please don't think I say this to scare your daughter or to make you think she shouldn't have brought her case. I'm noy. I say it because by being poorly prepared, she could blow her case.
I'll say it again. It's brutal. It's nothing personal, but it is brutal.