Could it be, that the meals are done in a bad way for her? Did you ever ask her why she dont want to have meals instead of eating on her own?
Maybe she doesnt like, that there are so many people around her during the meal. Even more if she is forced to listen or talk to them. For this I have to fully concentrate on it, and its as if you would ask Schumacher to eat relayed a meal while driving a Formula One Race. So I hate invitation to big events in restaurants, because you get served a good meal, but then you are not allowed to eat it because you are told that you are rude when you are not listening and answering the others, then you haste a few bites in between every 10 minutes until its cold, and as punishment they force an discussion on you, why you didnt eat. -.-
The other Idea would be, that maybe some food are a problem for her digestive system, without her really knowing herself. My mom cooked separate stuff most of the time, so nothing special for me, but she was used on her own to not mix the food. As example there was flesh, there was a sauce in a sauciere, there were some pees extra and so on... If its mixed its too much different taste for me. So I usually eat them separate. Its not that I dont eat much different stuff, but never mixed. So today for midday meal it was an apple, a kiwi, two whole grain breads with cheese, a cooked egg and a salad of cucumber with garlic, pepper and yoghurt. If there are additionial flavor enhancers, i dont like it, because the taste normally gets too intensive for and tastes weird anyway. Same goes for too much fat, that also enhances taste. So cooked and mixed meals can be a great problem for me.
What did your daugher answer why she is prefering to eat on her own out of the fridge, instead of the meals?