I think you could certainly do a booster seat, just make sure it has straps you can still buckle her in to..my 15 month old uses one, and has since she was 12 months. And, as for the fits...mine head to their rooms if they need to pitch a fit, or they can sit nicely at the table. Will she fight..you bet, all out, screaming until you think she will pass out..but then, she will stop. She will realize after a few times that you are serious. The problem is, that right now, she knows that if she gets mad enough, you cave. For the sake of your sanity mind you, something all of us moms understand. But now, it is creating a problem, and so, the pattern must be changed. With mine, I only let them scream in their beds for a minute or two, go in, pick them up, and ask if they are ready to join us. Can she stop crying etc. And try again. I will say, I dont make my 1&2 year olds sit until we are all done, they are allowed to get down, but they are not allowed to ruin dinner for the rest of us. I wish you the best of luck!! I have 4 kids under 8 right now, and am pregnant with another one,so I know what 3 toddlers can do to you! ~A.~