It's one thing for you to understand your child's sensory integration problems, but getting your other children to extend appropriate understanding and sympathy is another. Depending on the age of your child's siblings, you may be able to give them a little bit of an explanation as to why their brother does those strange, annoying things. But any special treatment you give him to compensate for his sensory challenges is liable to meet with cries of “No fair!” from the others.
You'll be doing your children a service to teach them now that fair doesn't mean equal treatment for each person. It involves each person getting exactly what is appropriate for her. Talk about some ways in which your other children “get” things that your child with sensory integration disorder does not. Does the sibling participate in more activities? Have more friends? Have an easier time in school? It's not fair that your child has this disorder, it just is. “Fair” means she gets what she needs to be safe and happy and comfortable, and your other children get that, too.