That must be frustrating. I wish everyone could get along all the time too.
Luna (cat) and Sherman (kitten) are starting to be friends now, which is good. Though one time, she was nibbling out of his bowl and he tried to eat and she hissed at him and swatted. The funny thing is that I wish she'd do it when he muscles into her bowl! I am giving them separate bowls at feeding time b/c Luna is only allowed to have a can a day b/c she's tubby, but Shermie can have all the food he wants since he's growing. If he eats too much of hers, I may start feeding her too much and she'll gain weight again (it took her a while to lose 3.4 lbs, but doesn't take much time for her to gain it again!!
My "pet" peeve is that when Shermie goes to eat out of her bowl while she's eating, she'll usually just walk away. I don't want her to eat too much, but on the other hand I don't want her to eat to little and not get enough nutrittion.