C.K.
Firstly, I am sorry to hear of the children's loss. It must be extremely hard on everyone to adjust to not only the grief, but the new situations involving so much change. I did a search online, and there is a wonderful organization for children who have lost a loved one: http://www.thealcove.org/othergriefcenters.htm
Counseling is wonderful, but maybe a group like this can help them by healing with other children who truly know what they are experiencing. There are also books available on Amazon if you search for things like, when a parent dies, etc.
Blessings to you all....