K.R.
I was glad to see this question because my 9 month old little girl just started this. She has never really liked her swing much so we hardly ever use it. So I don't know if she would do the same thing with the swing. Sometimes she will fuss when I first put her in her highchair but nothing like the car seat. She will use her feet to try and push herself out of the car seat while she arches her back. It does make it quite difficult to buckle her in. I just gently but firmly hold her there while I buckle her in. She is small for her age so she still fits easily in her infant carrier. I have noticed that she doesn't do it quite as bad if I put her in the carrier while we are still in the house. Not sure why that matters for her but eventually we will have to switch to a seat that stays in the car so I don't want her to get used to that. She doesn't take a pacifier anymore so that won't work for us. I have found 2 things that work. If she is hungry, then sometimes she will take a cookie if I offer it to her. Other times she just throws it back while still crying. I have also found that singing helps her calm down once she is in the seat. It doesn't make any difference while putting her in the seat though. I have tried putting a variety of toys in the seat with her and she will toss each and every one out of the seat. Some of these are the same toys that a month or 2 ago she would happily hold during a car ride. I am really hoping this is just a stage that will pass.