954 This is an easy one. You just have to have will power. Pick whatever food you think is the healthiest and if she doesn’t eat it, too bad for her. At this age you can even skip her dinner if she doesn’t eat her breakfast, and she will think twice the next morning lol.
I know that sounds harsh, but i have had HUNDREDS of dogs in my care and I must always control their diet and know when there is food in their stomach to avoid problems while exercising.
Dogs are very smart and designed to be able to go longer periods without food than we are so you can’t blame them to hold out on you, if they think you’ll mix something in.
The other thing to troubleshoot is that you may simply be offering her too much food. The higher quality brands are actually very calorie dense and you will be surprised at how little she will need to eat.
Just remember dogs can go days and days without eating, she will not get sick from that. At worst she will drop a couple pounds before she learns to appreciate what you put down.