Your two year old is basically exerting her will and explanations are not particularly useful with this age group. I would plan a fun outing with your daughter (hopefully without the 5 year old so he does not feel punished). I feel kids learn the best early on from logical consequences. Tell her we are going _________ (something she really likes), put her in the car seat and start driving. If she gets out, stop the car in a safe place and put her back in and say, "You need to stay in the car seat until we get to ____________." Start driving and if she gets out again say, "We cannot go because you are not in your car seat and it is not safe. We are going home" Do not say anything else, don't yell, don't talk about it anymore, bite your tongue, go straight home and act as if you are continuing with your day as usual. She will probably tantrum and you will wonder if she really understood what happened. Trust me, she did! If she says, "I want to go now" in whatever way she communicates that, say "We will try tomorrow and see if you can stay in your car seat like a big girl." Period. This is not convenient with how life works but just make it your goal for two days to do this even if you have to leave your 5 year old with a friend. I think it will work. Let me know. Good luck and don't feel guilty! Car seats are not a choice and that is that. A.