J.,
First of all I want to say that I am sorry your daughter is so upset about not being able to start kindergarten with her cousin. That's tough to deal with for kids so close in age. With that being said, I am a kindergarten teacher here in Oregon and wanted a chance to stand up for Oregon education.
The main reason Oregon has set their entry date so early is because school starts in September and we want to make sure that all children entering kindergarten are ready. Not ready in an academic sense, ready in an emotional/social sense. Most 4 year olds are not developmentally ready, let alone socially ready to be in kindergarten.
It is wonderful that your child is already able to do so many things- that tells me you are a parent who cares and works with her. Kudos to you! Put her in pre-school/pre-k and let her develop those skills even more. Enroll her in some classes through the local Y or other places. I know in Amity they don't have a lot of choices but I'm sure McMinnville has a Y and if not, it might be worth it to take her into Salem. The Gilbert House in Salem is a wonderful place and has many classes you can sign her up for, as does Mission Mill Museum. I could keep going but...
My point is, even though she can't go to school yet there is no reason why you can't put her in "school settings." Putting her in her own classes will make her feel important. The fact that she would understand that her cousin is doing something different and that her cousin would tease her sounds like something you need to fix as a parent. That, personally, is not okay. Have you told her that the school won't take her because she's "not smart enough" or is that something she deduced herself? You need to change that thought. That's your responsibility to make sure your daughter feels good about school and understands that you can't just start school whenever you feel you're ready.
Take Disneyland for example. They have limits on what height a child can be to ride a ride. It's not because that child isn't good enough to ride the ride but it's a safety precaution for the child. In a round-about way it's the same with school. A 4 year old, even if they are almost 5 isn't usually ready and then you're putting them into a mix of kids that are 5 and almost 6. You're putting her at a serious disadvantage down the road.
Here's a thought that might set your blood to boiling and I apologize if it does- that's not my intent. As a kindergarten teacher I see a wide range of abilities walk through my door on the first day of school. This year I have a child who came in never having held a pencil before in his life (and that is not an exaggeration) and a child who is reading at an almost 3rd grade level. Tough to teach at the two ends of things, but it's my job. This isn't the first time I have had children like this. I track those children as they go through school and 9 times out of 10 that child who came in as low as can be and the child really high will be almost parallel by the time they reach third grade. Children who have many experiences in life and a good solid background generally come in higher than others, but they plateau out by about 3rd grade. This is because once a child is developmentally ready to learn the stuff they take off. Sometimes kids just need a nudge. Am I saying your child is not smarter than others- NO! Am I saying your child has had a great first 4 1/2 years of her life- YES! But putting her in school before she's age appropriate may cause there to be a bigger gap by the time she's in 3rd grade than you really want. It might not happen, but why take the chance? Why not let her be the top student in her class?
It also sounds like separating your daughter and the cousin might be something that needs to happen. They need to find out who they are without having each other to lean on. When I have "best friends" enter my classroom I work all year to try to get them to branch out but most of the time they stick to what they know. They don't generally learn the basics of what kindergarten is all about- meeting and learning about being with new people. They stick together and, though they'll have made new acquaintances, they still rely heavily on each other. Then they go to first grade and usually get put in different classes and they've got to make up a whole year of learning that basic skill of meeting and learning to be with new people.
Does any of this make sense? I am not saying that Oregon education has all the right answers. Believe me, as a teacher I have had my fill of Oregon education and it's "right" answers at times. But, as a kindergarten teacher I do stand by that date they set. I have a child this year who's birthday is one day after the cut-off so they squeaked in. That child is struggling. Yes, she knew how to write her name and could identify a pretty good portion of her letters but socially she's not as adept at the kindergarten thing as others in the class are. This may not be the situation with your child, but you need to work on changing her thoughts about why she can't start school yet and focus on the good parts of it. Enroll her in some of her own classes. Get her into her own thing. And please, don't ever say Oregon school's won't accept her because she's not smart enough.
I hope I haven't offended you and I hope some of what I've said makes sense. If not, I'm sorry.
Kindly,
M.