Bad carbs are bad carbs and they will do you harm. If you have 'fixed' dinner than at least she will be eating at least partially better and this is good.
The fat will help her stay fuller during the morning and she may eat less for breakfast and lunch anyway.
The carbs may help her put on weight, but she should see the benefits you are getting and if you explain that it is the carbs that cause the fat, she will have no choice but to go fully primal.
My wife still lost some weight by eating a fair amount of carbs (years ago), but it was fruit and veg. I don't think the same will apply for grains and potatoes.
You may have to rely on education and hope she doesn't go backwards much before she sees the light.
The "Seven Deadly Sins"
• Grains (wheat/rice/oats etc) . . . . . • Dairy (milk/yogurt/butter/cheese etc) . . . . .• Nightshades (peppers/tomato/eggplant etc)
• Tubers (potato/arrowroot etc) . . . • Modernly palatable (cashews/olives etc) . . . • Refined foods (salt/sugars etc )
• Legumes (soy/beans/peas etc)