I've had misophonia since I was a young child, mealtimes were always torture for me due to crunching, forks touching teeth or plates, slurping of drinks.
It wasn't diagnosed for another 15 years and in that time I used to melt down a lot when others were eating and spent a lot of time with musician grade earplugs as couldn't be seen due to my loads of hair.
To work in an office alongside that all day would have been hell, thankfully any offices I worked in had no food at desk rules and we had breaks which allowed us time to get food and drink, which were taken on a rota so i tended to let the worst offenders for me take the 1st slots while I went on 2nds or 3rds.
I googled how to manage misophonia in the workplace
www.jobboom.com/career/how-to-manage-misophonia-in-the-workplace/
Also with a diagnosis like misophonia, this is something which is causing problems day in day out, which isn't acceptable.
I say this in the same way, if I take from under my desk and liberally spray air freshener around to the point where everyone is wheezing and coughing and having asthma attacks, that would be seen as totally unacceptable but it is acceptable to trigger a condition you have been diagnosed with so you shouldn't be triggered constantly when there are ways around it - like a no desk eating policy for starters
Her eating may be affecting only you soundwise, but potentially her productivity will not be the same if she is eating at her desk during work time so therefore getting paid for less work.
As a pp suggested keep a note this would record how often this happens - how this is making you feel
Misophonia is horrible and is something which is not your fault
@SaucyJack Misophonia is not currently categorised and it was proposed in 2000 but has also been proposed as a symptom in 2015.
It currently doesn't fall under hearing and psychiatric disorders but some see it as a neurological condition
@Schroedingerscatagain hugs to you and your DD
to @Glowbuggy