This may be one of the hardest things to witness, experience as a parent who has lost a child. The home is so full of company and the parents are surrounded by loved ones as well as the kids. Somehow I feel the sibling of the lost child feel lost and hopeless. They are so worried about their parents that they seem to be consumed with that which delays their own grieving. The pain can be so hard to process as a child. Everything in their life has suddenly changed. Depending on the order of the ages in my case it was my oldest son. He was our go to son. The boys actual best friend.
Grief can be delayed for years and months in children before they are ready to show their emotion. When the time comes it may come out of nowhere and in the form of an unknown topic. Take a deep breath and listen. Their anger may be directed at you and you find yourself defending it or justifying it. The best way to handle is to listen with all of your heart to theirs. Give them time to express their pain.
This will break your heart and literally bring you to your knees. Losing a child before the parents go is an awful painful out of the order that is not suppose to happen. Then have brothers and sisters digesting it. Reassure them that you are human and you understand what they feel..