Sounds tough UBW
When ds2 started to get fussy and refusing foods (when he was about 2.5yo), I would still offer him a meal (the same as what we were all eating) and if he didn't eat it he wouldn't get anything else. He never once complained of feeling hungry after not having any dinner, so I just had to accept that he wasn't hungry and he was regulating his own intake. Either that or it was about control. The only thing young children and babies can control is what goes in their mouth.
But I didn't relent and he went back to eating everything again quite quickly. He still has the odd few days here and there when he doesn't eat his dinner, but he is big enough now to make and understand his own decisions.
But could I do the same with a 15mo? Gawd knows. But I was adamant that I was not going to back myself into a culinary corner and only offer him a meal that I knew he would eat, ie chips every day, when I knew that there were other foods that he liked but for whatever reason was stubbornly refusing.
Going back to 'they only thing that they can control is what they eat', I would also take the inevitable tension away from mealtimes. Even if you are seething inside, don't show it and stay calm - having a radio on helps I find. If your negative attention is what they are after, don't give it to them.
It's like a bloody battle field isn't it?