Awww, I'm sorry. It is very hard and that is why she had the meltdown I bet, that and just all the stimulation. If your dad asks why you are not coming around tell him the truth, you don't understand my child and do not want to take the time to understand her. What you do to her causes her actual pain and she does not know how to cope with it yet. Until you understand and take the time to learn what is wrong with your granddaughter we will have to stay away. Let him think about it. Than maybe your brother can talk to him too. IT does hurt, but I understand. My son used to be very aggressive he has beat up more people in his first 4 years of life then I have my whole life and I do Muay Thai kickboxing! lol I would tell people I understand if you do not want us around. He punched my friends daughter in the face one time and, oh wait TWICE second time was awful!!!! She was gushing blood everywhere!!!! Over a toy! He used to bite, scratch, it was awful!!!!! I am still on edge all the time, but not as bad. You know I think it comes with the territory, at least your brother does understand and is taking the time to learn, but at the same time he wants to keep his child safe as you do yours. So once you get your "sensory diet" in place and get some sense of control so to speak let it roll.
I personally tell people depending on the situation, my son knows what he has, I make weighted blankets and I had him design the logo and I made tags to put on them. He is so proud, he knows they go all over the country to help other kids feel better and to spread awareness. I believe that with education comes understanding, with understanding comes extreme patience ( lol). I don't just go around saying "My son has SPD, but if in an extreme case like someone is just plain ignorant I will tell them , if we are out somewhere and he is flipping out because he is extremely impatient. That is usually when he starts having a "potty mouth". HE has switched from hitting to being mouthy when he is getting impatient now.
What do I do...... Well sometimes bribery works! lol If we are going somewhere that I know will take a lot of time and will be hard for him I use the bribes ( I know might not be the best thing) He loves Lego mini figures, so sometimes I will have one on hand in package and if you can make it through what we have to do you will get this. Ummmm I have a warning chart where his tag will be moved so I will tell him " Do you want a warning?!?!" He will stop because at the third he has to do push ups. I try and catch meltdowns before they are going to happen. there is no excuse for teasing a child with issues or none, but with my son he takes everything literally and doesn't understand that so it is just plain mean! Whit a meltdown, I wouldn't call it misbehaving, it is something that is out of their control because they do not have the coping skills to deal with it. You have to remember ,especially with school that she is NOT a behavior problem or she will be labeled as such! She has "problems" that cause her behaviors. If I know it is a situation that is to overstim for him I will take him away for small breaks so he can "regroup", if he is getting lippy I will give him the warning, but you need to have a warning system in place that they are aware of, so they think " Oh boy when I get home my warning chart will be moved or whatever" I bought a pocket folder and made a mini one to take along with me, and for the sitters house. Always bring along their calming tools, weighted blanket, favorite book, etc... whatever it is that helps them to calm down. I can feel your stress, it weighs so heavily. I never could ever sit down when we went somewhere, I still won't leave him places. He started scouts and I won't leave, he gets too excited and then he gets really loud and lippy! the scout leader is too laid back, not happening and the other leader had a smart mouth with him and I told her off! She told him " I don't want to hear you" Then she looked at me and said I say that to all my boys, I told her "Well I don't say it to mine and you won't either' Then told her what he has, she felt like a big JERK!
I have the out of sync child has fun and I do like it! I used to use the game all the time with holding up the wall! Especially if we had to wait somewhere in a line, we would play it while we waited! lol Talk about looking strange! But it worked and hey you get to the point where you will do what you have to!!!! I always still take a bag of things with me just in case!! We have to wait 8 min in the car after I pick him up from school then go get my other son from his school. It is the LONGEST time ever! If I forget to bring something it is like 8 hours! " I'm thirsty, I'm hungry, " Then I am like we will be home soon, " BUT IT I AM NOW!!!!!!!!!!!!!" SHEESH! So I grab a drink and snack with his Nintendo ds or a book! lol Should he learn to wait, sure, he know there are things he has to wait for and he knows it. Something else that might help her is something like under armor or something like it. It is soft material, but it hugs them. She can wear them under her clothes. My son's OT told me to have him wear those, my friend's son has SPD also ( get those two together!!!! PHEW!!!!)he wears them all the time!

You are going to hear things that are going to hurt, I think the worst thing I heard was another kid call my son crazy on the playground. All he wanted to do was join in and this little punk called him crazy. That broke my heart in pieces. Adults, that is just ignorance they should know better, if not educate yourself. You need to look at it from your brother's perspective his child is very young, but this is a learning experience for your daughter as well. If she likes to be around her then talk to her. You can't be around your cousin right now you have to remember she is a baby and can get hurt, you have to be careful around her, etc.... They don't know how hard they are doing things, to them it could be light as a feather but actually feels like a rock fell on you! Things will fall into place, it will just take time. My biggest advice to you is with others, always be an advocate and have her back, she cannot defend herself from stupid adults you will have to, school will be a challenge believe me! Never allow them to label her behavioral, she does not have a behavior problem, she has a sensory problem. If you need anything please write I know what you are feeling and it is a very heavy feeling, but it will get better, believe me! Have a good one!!!!!!!! Heather