Reach out to the bereaved so they won't have to grieve alone!
Wise words from members of the Compassionate Friends ~ When a sibling passes, the surviving siblings tend to experience a loss of self. When you know someone from birth, your identity is based on having them there. When they pass away, the strengths that the deceased sibling lent to the surviving siblings are gone and they must learn how to continue with out those strengths or find them within themselves. They must continue with their life and move toward the future even though they have lost a big part of that future when they lost their sibling. Usually, most events, including births, holidays, weddings, etc. forever after are bittersweet.
Siblings sometime don't feel validated in their grief. Some outsiders will understand the parent's grief, but expect the siblings to "get over" the death quickly. Depending on age, if the sibling that passed and the surviving siblings are young, the surviving siblings may feel different from their peers and alone, which will often lead to some form of depression.
Dealing with the death of a sibling can be very difficult, especially with out help. If you or someone you know is grieving the loss of sibling, remember it takes time to heal, and the pain doesn't go away. However, with support, surviving siblings can grow through the grieving process and come out on the other side with a better understanding of themselves and the roll they play in their family.