I have had a similiar situation in the last week, except instead of a family member, it was my best friends dad (my son is VERY close to her), and he is not special needs. What are the special needs of the child? In that situation, I might talk to a doctor for advice, or even go to a counselor to talk about it to make sure they understand and can get through it with as little stress as possible.
My son is 4, and I took him to a wake last Sunday. I wasn't sure about it, but I didn't think keeping him from dealing with it would be the best for him in the long run either, so I brought him. He has been asking questions about death for months now, so much that one time we were in line at Target and there were long lines all around us, and out of nowhere, he loudly asked "Mommy, when are all these people going to die?" I was very embarassed and just told him we would talk about it when we got in the car. It is a hard subject for kids to understand, and in my situation, it helped him a lot to go to the wake. He was very curious in seeing, he had a lot of questions, and we just stood there with him and answered them and then asked if he had any more questions. He learned a lot and actually understands what death is now. We told him that your soul leaves your body and goes to heaven with God (being in a christian daycare really helped with that part), and just gave him the best answer we could to every question he had. He was very serious the whole time, and really seemed to get it. Then we went home and as he was going to bed he was telling me that God was going to make him again tomorrow (he didn't get that it was permanent), so I explained that it doesn't work that way, he got scared and started to cry so I explained to him that Heaven is a very happy place because you get to be with God and he loves you, and from Heaven you can look down and see everyone that is still alive, and that someday we will die too and go to Heaven and see the people we have lost, and he really liked that, I was afraid of nightmares that night, but he slept great and so far has not seemed scared of death since. The best way for him to get his questions answered was to see it, and to know what it means when I tell him that you aren't alive anymore and can't talk or breathe or do anything (he didn't really understand what that meant until he saw it). I know this is a hard thing to deal with. Hard enough to deal with yourself, and making sure a child has the best experience possible is hard to do while grieving. I hope everything goes well, if you need to talk I am here.