QUESTIONS:
Q1. Is Dad a business analyst in the muggle world or the magical world or is dad a tradesman in magical artefacts? And not a business analyst?
Q2. Who are these people who attacked Mom, Dad and Maeve on their way to a party?
USE OF FIENDFYRE:
By stating that they used Fiendfyre means they are either very powerful dark witches/wizards to control it, or they can't control it all which brings up the following point:
"The extremely volatile and sentient cursed fire spread rapidly, and incinerated nearly everything through mere physical contact." If any part of Maeve catches fire from Fiendfyre, Maeve is likely dead and incinerated with it. There wouldn't be time for anyone to come to her rescue as you've also written her as passed out due to her mom pushing her away to the ground to save her from this ordeal. Based on canon knowledge about Fiendfyre, she wouldn't survive it the way you've added it in.
This is the only part of the application we are having trouble understanding, comprehending and making work because she should be deceased.
ALTERNATIVE SUGGESTION FOR FIENDFYRE:
The level of injury you want for Maeve would be more likely caused by a deep cut, perhaps a diffindo improperly used which causes severe gouges in items and should not be used on humans but would cut deep enough to cause the nerve damage you are looking for.
Regular fire might cause some level of nerve damage but there are enough healing advancements in both worlds that Maeve would more than likely be fine. There is a chance that nerve damage could occur in third-degree burns but you will need to clarify where the nerve damage is because you claim the burns are on her left thigh and forearm but the nerve damage is in her hip. Please clarify this part in the 'Special Situations'.
Maeve Mancini