I totally understand this. I have five kids 9,7, 4, 2.5 and 17 months. At one point or another all the kids hav efelt this way. We try very hard to spend time one on one even if it's jsut to walk to the mailbox and back (about 5 minutes with each of the kids and also include activities that each of the kids enjoy in our family routine. We also explain as best we can that not everything is right for everyone. This became really apparent this last year as our two year old had many medical issues. Our 4 year old boy wanted to be in the hospital too and has even asked for a feeding tube in his stomach that he can get special food through. This broke my heart to hear him say this. We told him that although his sister needs this and mommy and daddy need to stay with her when she is at the hospital we love him very much too and try to give him extra hugs and stories at bedtime. Although the first two did not do preschool we did enroll our 4 year old, partly out of necessity as I was often at the doctors and partly so he can have something that belongs to him. Perhaps when big sister has a dance recital, little brother can put on a performance at home or at the park for grandparents and other special people who come to the recital. Make a big deal and brign cupcakes to celebrate HIS accomplishment even if is being super-fast on the slide. Most of all love you kids and do your best and it will all work out.