I have been an active Mormon most of my life (and that is a long, long time) and I have never heard that we are to pray for the dead.  We do seal our families together inorder for us to be together after death, (if those family members choose to accept the sealings, we do not take anyone's agency away from them alive or dead, but some things have to be done on earth and we want to offer this to those who may have missed it).  I never cease to be amazed at what others tell me I believe when they themselves have never checked on LDS beliefs from LDS members.  The one that amazes me most is when I am told I don't believe in Christ--- Cindy Hearn Mahavier